Process for the modification of polymers, in particular polymer nanoparticles

ABSTRACT

A process for the preparation of modified polymers by a photo-initiated polymerization includes preparing a polymerization medium comprising at least one photoinitiator comprising at least one phosphorous oxide (P═O) group or at least one phosphorous sulfide (P═S) group, and at least one polymerizable monomer. The at least one polymerizable monomer is polymerized by irradiating the polymerization medium with electromagnetic radiation so as to induce a generation of radicals so as to obtain a polymer. The polymer is modified by irradiating the polymer with electromagnetic radiation so as to induce a generation of radicals from the polymer in a presence of at least one modifying agent.

CROSS REFERENCE TO PRIOR APPLICATIONS

This application is a U.S. National Phase application under 35 U.S.C.§371 of International Application No. PCT/EP2011/005205, filed on Oct.17, 2011 and which claims benefit to European Patent Application No.10013760.3, filed on Oct. 19, 2010. The International Application waspublished in English on Apr. 26, 2012 as WO 2012/052147 A1 under PCTArticle 21(2).

FIELD

The present invention relates to a highly efficient process for thephoto-initiated preparation of polymers by polymerization usingphotoinitiators comprising a phosphorous oxide or -sulfide group andmodification of said polymers. In particular, the present inventionrelates to an ultra-fast process for the photo-initiated preparation oflattices comprising polymer nanoparticles by heterophase polymerizationusing photoinitiators comprising a phosphorous oxide or -sulfide groupand their modification. In another aspect, the present invention relatesto polymers and polymer nanoparticles obtainable by said process.

BACKGROUND

Polymers, in particular, lattices or polymer particles obtainedtherefrom are widely used as coatings, adhesives, ink and paintingmaterials, for precision mold constructions and the manufacture ofmicro-sized materials.

For the latter, the unique properties of micro- and nanoscaled polymerparticles with specific properties such as defined molecular weightdistributions and polydispersities have meanwhile gained furthersignificant attention not only in the electronics industry, for example,in the manufacture of TFT and LCD displays, digital toners and e-paper,but also in the medical sector such as for drug delivery systems,diagnostic sensors, contrast agents and many other fields of industry.

Polymer nanoparticles are frequently synthesized by physical methodslike evaporation of polymer solution droplets or, in particular, forcommercially important polymers such as polystyrene andpoly(meth)acrylates, by direct synthesis of nanoparticles using specialpolymerisation processes. The most common processes are heterophasepolymerisations, in particular, thermally or photo-initiated emulsionpolymerizations.

Over the last decades, efforts were made to develop heterophasepolymerization processes and/or post polymerisation modifications inorder to achieve better control over molecular weight distribution,particle size of primary polymer nanoparticles, the crosslinkingbehavior of polymers or polymer nanoparticles or the introduction ofpolymer end groups.

Emulsion polymerisations induced by X-ray radiation are described in S.Wang, X. Wang, Z. Zhang, Eur. Polym. J., 2007, 43, 178.

Emulsion polymerisations induced by UV/Vis radiation are described in P.Kuo, N. Turro, Macromolecules 1987, 20, 1216-1221, wherein the formationof polystyrene nanoparticles having a weight average molecular weight of500 kg/mol or less is disclosed.

In T. Ott, Dissertation ETH Zürich No. 18055, 2008, Chapter 6, batchemulsion polymerisations induced by photofragmentation ofbisacylphosphines are investigated in detail. However, high monomerconversion typically requires irradiation times of more than 2 hours.

A. Chemtob et al. describes a batch process (in a cuvette) for thepreparation of lattices comprising copolymers by irradiating aminiemulsion of nanodroplets comprising acrylic acid, butylacrylate andmethylmethacrylate encapsulating high amounts (4 wt.-%) of a hydrophobicphotoinitiator of the BAPO type (BAPO=bisacylphosphine oxide).

WO 2005/042591 A describes a process for preparing polymers with definedend group functionalities which comprises polymerizing monomers in aheterophase medium and in the presence of a water-soluble photoinitiatorsystem bearing said desired end group. The end group is deliberated asstarter radical for chain propagation upon photofragmentation of thephotoinitiator.

A major disadvantage is the use of methylene blue or other coloredand/or toxic compounds and the low variability of end groups.

EP 1 300 427 A describes a process for preparing hot melt adhesiveswhich comprises polymerisation of acrylates in the presence of commonphotoinitiators and control agents such as thioesters, trithiocarbonatesor dithioesters in order to provide enhanced crosslinking ability uponUV-irradiation.

A major disadvantage is the use of high amounts of different compoundsnecessary to achieve the desired properties.

OBJECT

An aspect of the present invention is to provide a process for theefficient and easily controllable post-polymerization modification ofpolymers, in particular, of lattices or polymer nanoparticles.

In an embodiment, the present invention provides a process for thepreparation of modified polymers by a photo-initiated polymerization,the method comprising:

A) preparing a polymerization medium comprising:

-   -   at least one photoinitiator comprising at least one phosphorous        oxide group (P═O) or at least one phosphorous sulfide (P═S)        group, and    -   at least one polymerizable monomer;

B) polymerizing the at least one polymerizable monomer by irradiatingthe polymerization medium with electromagnetic radiation so as to inducea generation of radicals so as to obtain a polymer; and

C) modifying the polymer obtained in step B) by irradiating the polymerwith electromagnetic radiation so as to induce a generation of radicalsfrom the polymer in the a presence of at least one modifying agent.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention is described in greater detail below on the basisof embodiments and of the drawings in which:

FIG. 1 shows the irradiation of the surface (S) a of a thin film ofpolymerization medium (PM) having a uniform layer thickness (L);

FIG. 2 shows a transparent round tube having an inner radius (r)irradiated from one direction (the dashed part of the surface is notirradiated);

FIG. 3 shows a transparent round tube having an inner radius (r)irradiated from two directions;

FIG. 4 shows an exemplary, simplified flow diagram of a processaccording to the present invention using a flow through reactor;

FIG. 5 shows a detailed cross-sectional view of a flow-through reactorused to carry out the experiments of the present invention;

FIG. 6 shows FT-IR spectroscopic analyses of the lattices of Examples 1and 3 and of the modified polymers after performing step C);

FIG. 7 shows the molecular weight distribution (MWD) of the modifiedpolymers determined by size exclusion chromatography (SEC);

FIG. 8 shows the unmodified precursor polymer produced in Examples 8 and9 via bulk polymerization in curves 1 and 2, and the molecular weightdistribution of the modified polymer obtained thereby in curve 3;

FIG. 9 shows the onset of polymerization in Example 11 via theoccurrence of a slight turbidity; and

FIG. 10 shows the sequence of letters ‘SRG’ phototyped through a PTFEstencil using a 50 wt.-% solution of the polymer obtained in Example 9purified as described in Example 10 in a styrene-butylacrylate mixture(3:2 g/g) with a small amount of a yellow dye.

DETAILED DESCRIPTION

In an embodiment of the present invention, the process encompasses aprocess for the preparation of modified polymer nanoparticles formed byphoto-initiated heterophase polymerization which comprises at least thesteps of:

A) preparing a heterophase medium comprising at least a dispersed phaseand a continuous phase and at least

-   -   one or more surfactants    -   one or more photoinitiators    -   one or more polymerizable monomers    -   and

B) polymerizing the one or more polymerizable monomers by irradiatingsaid heterophase medium with electromagnetic radiation having awavelength sufficient to induce the generation of radicals to obtainlattices comprising polymer nanoparticles

whereby the photoinitiators are selected from compounds comprising atleast one phosphorous oxide (P═O) or phosphorous sulfide (P═S) group,and

C) modifying the lattices or polymer nanoparticles obtained in step B)by irradiating said lattices or polymer nanoparticles withelectromagnetic radiation having a wavelength sufficient to induce thegeneration of radicals from said lattices or polymer nanoparticles inthe presence of at least one modifying agent.

The scope of the present invention encompasses all combinations ofsubstituent definitions, parameters, features and illustrations setforth above and below, either in general or within areas of preferenceor preferred or alternative embodiments, with one another.

Whenever used herein the terms “including”, “for example”, “e.g.”, “suchas” and “like” are meant in the sense of “including but without beinglimited to” or “for example without limitation”, respectively.

The terms “latex” and “lattices” denote suspensions, for example,aqueous suspensions, comprising polymer nanoparticles having an averageparticle size of 1 to 10,000 nm, for example, 5 to 1,000 nm, forexample, 10 to 200 nm and, for example, 10 to 100 nm.

The term “polymer nanoparticles” denotes polymer nanoparticlescomprising, for example, at least 10 wt.-%, for example, at least 50wt.-%, for example, at least 80 wt.-% and, for example, at least 90wt.-% of a polymer, and, for example, consisting of a polymer.

The average particle size as used herein is defined as being theparticle size measured using dynamic light scattering (DLS), which isalso known as photon correlation spectroscopy (PSC) or quasi-elasticlight scattering (QELS). The particle size measured thereby is alsofrequently called hydrodynamic diameter and reflects how a particlediffuses within a fluid. The measured hydrodynamic diameter isequivalent to that of an ideal sphere having the same translationaldiffusion coefficient as the particle being measured. Since the surfacestructure may have a significant influence, the hydrodynamic diametermeasured using DLS can be significantly larger than the true diametermeasured e.g. by electron microscopy.

In Dynamic Light Scattering (DLS), the polydispersity index (PDI)reflects the width of the particle size distribution. It ranges from 0to 1. A value of zero refers to an ideal suspension with no distributionin size. Distributions with PDI values of 0.1 or smaller are calledmonodisperse while dispersions with values between 0.1 and 0.3 areconsidered as having a narrow size distribution. Dispersions having aPDI larger than 0.5 are considered as polydisperse.

Particle sizes referred to herein were obtained using a Nicomp particlesizer (PSS Santa Barbara, USA, model 370) at a fixed scattering angle of90°.

To distinguish the particle size PDI obtained by DLS from thepolydispersity index reflecting the molecular mass distribution of apolymer sample (M_(w)/M_(n)), the former is abbreviated as “DLS-PDI” andthe latter as “M-PDI”.

The Polymerization Medium

The polymerization according to step B) can be effected in any mannerknown to those skilled in the art which means for example either as bulkor solution polymerization or as heterophase polymerization in aheterophase medium.

If the polymerization is carried out as bulk or solution polymerizationthe polymerization medium comprises at least one or more photoinitiatorscomprising at least one phosphorous oxide (P═O) or phosphorous sulfide(P═S) group and one or more polymerizable monomers as defined andspecified in the sections “the photoinitiators” and “the polymerizablepolymers” hereinbelow.

In this case the one or more photoinitiators are for example mixed withthe one or more polymerizable polymers and polymerized in step B) asdescribed in the section “the polymerization conditions” hereinbelow.

Where solution polymerization is employed the polymerization mediumcomprises at least one or more photoinitiators comprising at least onephosphorous oxide (P═O) or phosphorous sulfide (P═S) group, one or morepolymerizable monomers as defined and specified in the sections “thephotoinitiators” and “the polymerizable polymers” hereinbelow and atleast one solvent.

In this case the weight ratio of solvent to polymerizable monomer in thepolymerization medium is typically of from 1:100 to 100:1, for example,of from 1:5 to 50:1, for example, from 1:1 to 5:1.

As solvents, all compounds capable of dissolving the polymerizablemonomers in the intended amounts can be used and which are not radicallypolymerizable and thus virtually inert under the reaction conditionsemployed.

Examples of solvents include:

-   -   ethers like for example alkyleneglycolethers such as        ethyleneglycoldimethyl- or diethylether, tetrahydrofurane,        diethylether, 1,4-dioxane and tert.-butylmethylether;    -   aromatic and aliphatic hydrocarbons like petrolethers, pentane,        hexane, cyclohexane, heptane, benzene, toluene and xylenes;    -   halogenated aromatic and aliphatic hydrocarbons like        chlorobenzene, dichlor-obenzenes, chloromethane or        dichloromethane;    -   nitriles such as acetonitrile, propanitrile or benzonitrile; and    -   esters and amides such as dimethylformamide, dimethylacetamide,        N-methylpyrrolidone, acetic acid methyl- and ethylester.

In an embodiment of the present invention, the type and amount ofsolvent is chosen so that the polymer formed during polymerization iskept in solution to 80 wt.-% or more, for example, 90 wt.-% or more,and, for example, 95 wt.-% or more.

In an embodiment of the present invention, the type and amount ofsolvent is chosen so that the polymer formed during polymerizationprecipitates from the solution in an amount of 50 wt.-% or more, forexample, 75 wt.-% or more, and, for example, 90 wt.-% or more.

The weight ratio of photoinitiator to polymerizable monomer in thepolymerization medium is typically of from 1:1 to 1:100,000, forexample, between 1:5 and 1:100,000, for example, between 1:10 and1:10,000, and, for example, 1:50 to 1:2,000.

In an embodiment of the present invention, where bulk or solutionpolymerization are applied the weight ratio of photoinitiator topolymerizable monomer in the polymerization medium is typically of from5:1 to 1:10,000, for example, from 2:1 to 1:5,000, for example, from 1:1to 1:1,000, and, for example, from 1:2 to 1:500.

The Heterophase Medium

In an embodiment of the present invention, a heterophase medium isemployed in steps A) and B). In step A), a heterophase medium comprisingat least a dispersed phase and a continuous phase is then prepared,whereby the heterophase medium further comprises one or moresurfactants, one or more polymerizable monomers and one or morephotoinitiators comprising at least one phosphorous oxide (P═O) orphosphorous sulfide (P═S) group.

As used herein, the term “heterophase medium comprising at least adispersed phase and a continuous phase” includes any type of mediumcomprising at least two phases forming an interface between thecontinuous phase and the dispersed phase. This includes suspensions andemulsions of any type referred to in the literature such as classicalemulsions, microemulsions and miniemulsions. The preparation ofemulsions in step A) is preferred.

It is apparent to those skilled in the art, that upon performance ofstep B), the heterophase medium may undergo a transition, for example,from an emulsion to a suspension.

The heterophase medium prepared in step A) may either comprise one ormore solid phases or not.

In an embodiment of the present invention, the heterophase mediumcomprises solid materials within the ranges given above which areintended to be encapsulated by the polymers formed duringpolymerization.

Such solid materials may comprise inorganic compounds or organiccompounds which are either not or not completely soluble in theheterophase medium.

In an embodiment of the present invention, the heterophase mediumprepared in step A1) comprises a solids content of from more than 0 to50 wt.-%, for example, from more than 0 to 25 wt.-%, for example, frommore than 0 wt-% to 10 wt.-%, and, for example, from more than 0 wt.-%to 2 wt.-%.

In an embodiment of the present invention, the heterophase mediumcomprises at least two liquid organic phases or a liquid aqueous phaseand a liquid organic phase, whereby in an embodiment, the liquid aqueousphase represents the continuous phase and the liquid organic phaserepresents the dispersed phase.

In an embodiment of the present invention, an aqueous phase, forexample, an aqueous continuous phase, comprises water and either atleast one water miscible organic solvent or not.

As used herein, the term water miscible organic solvent denotes organicsolvents which are miscible with water in any ratio.

Suitable water miscible organic solvents include aliphatic alcohols,glycols, ethers, glycol ethers, pyrrolidines, N-alkylpyrrolidinones,N-alkyl pyrrolidones, polyethylene glycols, polypropylene glycols,amides, carboxylic acids, esters, sulfoxides, sulfones, hydroxyetherderivatives such as butyl carbitol or cellosolve, amino alcohols, etherssuch as tetrahydrofurane and dioxane, ketones, and the like, as well asderivatives thereof and mixtures thereof, provided, however, that theyare miscible with water in any ratio.

Specific examples include methanol, ethanol, propanol, tetrahydrofurane,dioxane, ethylene glycol, propylene glycol, diethylene glycol, glycerol,dipropylene glycol or mixtures thereof.

The addition of water miscible organic solvents might be useful in thosecases where low polymerization temperatures shall be employed or wherethe partition of the photoinitiator between the phases or the monomersolubility in the phases shall be adjusted.

In addition thereto, the solubility of hydrophobic polymerizablemonomers within the aqueous continuous phase is typically raised so thatthe reaction rate, the particle size and the average molecular weightcan be influenced by the added amount of water miscible organic solvent.

The addition of water miscible organic solvents furthermore allows thereaction temperature to be lowered significantly below the freezingpoint of water or an aqueous phase.

In an embodiment of the present invention, the aqueous phase, forexample, the aqueous continuous phase, comprises either 0 wt.-%, or frommore than 0 to 20 wt-% of water-miscible organic solvents.

If water miscible solvents are employed, their content in an aqueousphase, in particular an aqueous continuous phase can, for example, bemore than 0 to 10 wt-%, for example, more than 0 to 5 wt-% and, forexample, more than 0 to 2 wt.-%.

In an embodiment of the present invention, the solubility of hydrophilicpolymerizable monomers within the aqueous continuous phase canoptionally be lowered by dissolving salts such as inorganic salts likesodium chloride and the like. The content of salts may in this caseamount to for example more than 0 to 5 wt.-%, for example, from 0.1 to 3wt.-%.

If water is applied as a dispersed or as a continuous phase, the pHvalue of the aqueous phase is typically in the range of 3 to 10, forexample, in the range of 5 to 9 measured or calculated on standardconditions.

The preparation of the heterophase medium is typically effected bysimply mixing the components by standard mixing elements such asagitators, static mixers or combinations thereof such as rotor-statormixers. Even though not typically necessary, the mixing can be supportedby using high force dispersion devices such as, for example, ultrasoundsonotrodes or high pressure homogenizers.

In an embodiment of the present invention, the mixing results in anumber average droplet size of below 100 μm, for example, between 5 and50 μm, as measured by light microscopy imaging.

The preparation of the heterophase medium in step A) may either beperformed batchwise or continuously.

The heterophase medium comprises one or more surfactants. Suitablesurfactants are, for example, non-ionic, cationic or anionic oramphoteric surfactants.

Anionic surfactants include C₆-C₂₄-alkyl sulfonates which are either notor once substituted by C₆ to C₁₄ aryl, C₆-C₂₄-fluoroalkyl sulfonates,C₆-C₁₈-alkyl ether sulfonates, C₆-C₁₄-aryl sulfonates, C₁-C₂₄-alkylsuccinates, C₁-C₂₄-alkyl sulfo succinates,N—(C₁-C₂₄-alkyl)-sarkosinates, acyltaurates, C₆-C₂₄-perfluoroalkylcarboxylates, C₆-C₂₄-alkyl phosphates, C₆-C₂₄-alkyl ether phosphates,C₆-C₂₄-alkyl ether carboxylates, in particular, the alkali metal,ammonium-, and organic ammonium salts of the aforementioned compounds.

Cationic surfactants include quarternary ammonium salts or pyridiniumsalts.

Non-ionic surfactants include polymeric surfactants of the block andgraft copolymer type such as triblock copolymers commercially availableand commonly known as pluronics (BASF SE) and synperonics (ICI)comprising two blocks of poly(ethylene)oxide and one intermediatepoly(propyleneoxide) block or “inverse pluronics” and “inversesynperonics” comprising two blocks of poly(propyleneoxide) and oneintermediate poly(ethylene)oxide block. Non-ionic surfactants furtherinclude homopolymers of ethyleneoxide and propyleneoxide and ethoxylatedand/or propoxylated sugars, phenols or hydroxyl fatty acids. Non-ionicsurfactants further include statistical polymers such as those describedin WO 2005/070979 A.

In an embodiment of the present invention, at least one surfactant isselected from the group consisting of sodium lauryl sulfonate, ammoniumlauryl sulfonate, sodium lauryl ether sulfonate, ammonium lauryl ethersulfonate, sodium lauryl sarkosinate, sodium oleyl succinate, sodiumdodecylbenzene sulfonate (SDS), triethanolamine dodecyl benzenesulphate, cetyltrimethylammonium bromide, cetylpyridinium chloride,polyethoxylated tallow amine, benzalkonium chloride and benzethoniumchloride.

In an embodiment of the present invention, one or more photoinitiatorsmay themselves serve as a surfactant if comprising C₆-C₂₄-alkyl whichare either not or once substituted by C₆ to C₁₄ aryl, C₆-C₂₄-fluoroalkylor C₆-C₂₄-alkyl ether substituents.

The weight ratio of surfactant and the continuous phase is typicallybetween 1:10,000 and 1:5, for example, between 1:100 and 1:20, wherebythe amount should be at least equal or higher than the critical micelleconcentration (CMC) in the heterophase medium. The CMC is defined asbeing the lowest concentration of surfactant at which micelle formationis observed and which is dependent on the nature of the surfactant usedand the heterophase medium employed.

In an embodiment of the present invention, the amount of surfactantemployed is at least four times, for example, at least eight times and,for example, at least twelve times higher than the CMC.

The weight ratio of the continuous phase and the dispersed phase dependson the surface energy and the phase inversion point but is typicallybetween 1:2 and 500:1, for example, between 1.5:1 and 20:1.

The Photoinitiators

The polymerization medium, in particular, the heterophase medium furthercomprises one or more photoinitiators comprising at least onephosphorous oxide (P═O) or phosphorous sulfide (P═S) group.

Examples of photoinitiators are those of formula (I):

-   -   wherein    -   n is 1 or 2 or a higher integer,    -   m is 0, 1 or 2,    -   X is sulphur or oxygen,    -   R¹, if n=1 is C₆-C₁₄-aryl or C₃-C₁₄-heterocyclyl, or        -   is C₁-C₁₈-alkoxy, —N(R⁴)₂, C₁-C₁₈-alkyl, C₂-C₁₈-alkenyl or            C₂-C₁₈-alkinyl,        -   which is either not, once, twice or more than twice            interrupted by non-successive functional groups selected            from the group consisting of:        -   —O—, —S—, —SO₂—, —SO—, —SO₂NR⁴—, NR⁴SO₂—, —NR⁴—,            —N⁺(R⁴)₂An⁻-, —CO—, —O(CO)—, (CO)O—, —O(CO)O—, —NR⁴(CO)NR⁴—,            NR⁴(CO)—, —(CO)NR⁴—, —NR⁴(CO)O—, —O(CO)NR⁴—, —Si(R⁵)₂—,            —OSi(R⁵)₂—, —OSi(R⁵)₂O—, —Si(R⁵)₂O—,        -   and which is either not, once, twice or more than twice            interrupted by bivalent residues selected from the group            consisting of C₃-C₁₄-heterocyclo-diyl,            C₃-C₁₄-heterocyclo-diylium⁺An⁻ and C₆-C₁₄-aryldiyl,        -   and which is not, additionally or alternatively, either            once, twice or more than twice substituted by substituents            selected from the group consisting of:        -   halogen, cyano, azido, vicinal oxo (forming epoxides),            vicinal NR⁵ (forming aziridins), C₆-C₁₄-aryl, C₁-C₈-alkoxy,            C₁-C₈-alkylthio, hydroxy, —SO₃M, —COOM, PO₃M₂, —PO(N(R⁵)₂)₂,            PO(OR⁵)₂, —SO₂N(R⁴)₂, —N(R⁴)₂, —N⁺(R⁴)₃An⁻,            C₃-C₁₄-heterocyclylium⁺An⁻, —CO₂N(R⁴)₂, —COR⁴, —OCOR⁴,            —NR⁴(CO)R⁵, —(CO)OR⁴, —NR⁴(CO)N(R⁴)₂, NR⁴SO₂R⁴,            —Si(OR⁵)_(y)(R⁵)_((3-y)), —OSi(OR⁵)_(y)(R⁵)_((3-y)) with            y=1, 2 or 3,    -   R¹, if n=2 is C₆-C₁₅-aryldiyl or C₃-C₁₄-heterocyclo-diyl        -   is C₁-C₁₈-alkanediyl, C₂-C₁₈-alkenediyl or            C₂-C₁₈-alkinediyl,        -   which is either not, once, twice or more than twice            interrupted by non-successive groups selected from the group            consisting of:        -   —O—, —S—, —SO₂—, —SO—, —SO₂NR⁴—, NR⁴SO₂—, —NR⁴—,            —N⁺(R⁴)₂An⁻-, —CO—, —O(CO)—, (CO)O—, —O(CO)O—, —NR⁴(CO)NR⁴—,            NR⁴(CO)—, —(CO)NR⁴—, —NR⁴(CO)O—, —O(CO)NR⁴—, —Si(R⁵)₂—,            —OSi(R⁵)₂—, —OSi(R⁵)₂O—, —Si(R⁵)₂O—,        -   and which is either not, once, twice or more than twice            interrupted by bivalent residues selected from the group            consisting of C₃-C₁₄-heterocyclo-diyl,            C₃-C₁₄-heterocyclo-diylium⁺An⁻ and C₆-C₁₄-aryldiyl,        -   and which is not, additionally or alternatively either once,            twice or more than twice substituted by substituents            selected from the group consisting of:        -   halogen, cyano, azido, vicinal oxo (forming epoxides),            vicinal NR⁵ (forming aziridins), C₆-C₁₄-aryl, C₁-C₈-alkoxy,            C₁-C₈-alkylthio, hydroxy, —SO₃M, —COOM, PO₃M₂, —PO(N(R⁵)₂)₂,            PO(OR⁵)₂, —SO₂N(R⁴)₂, —N(R⁴)₂, —N⁺(R⁴)₃An⁻,            C₃-C₁₄-heterocyclylium⁺An⁻, —CO₂N(R⁴)₂, —COR⁴, —OCOR⁴,            —NR⁴(CO)R⁵, —(CO)OR⁴, —NR⁴(CO)N(R⁴)₂, NR⁴SO₂R⁴,            —Si(OR⁵)_(y)(R⁵)_((3-y)), —OSi(OR⁵)_(y)(R⁵)_((3-y)) with            y=1, 2 or 3,        -   or is bivalent bis(C₆-C₁₅)-aryl, which is either not or once            interrupted by groups selected from the group consisting of:        -   —O—, —S—, —SO₂—, —SO—, C₄-C₁₈-alkanediyl, C₂-C₁₈-alkenediyl,    -   R¹, if n is an integer larger than 2        -   is a polymeric backbone having n binding sites to residues            of formula (I) given in brackets labelled with n    -   R², is C₆-C₁₄-aryl or C₃-C₁₄-heterocyclyl or        -   is C₁-C₁₈-alkyl, C₂-C₁₈-alkenyl or C₂-C₁₈-alkinyl,        -   which is either not, once, twice or more than twice            interrupted by non-successive functional groups selected            from the group consisting of:        -   —O—, —NR⁴—, —N⁺(R⁴)₂An⁻-, —CO—, —OCO—, —O(CO)O—, NR⁴(CO)—,            —NR⁴(CO)O—, O(CO)NR⁴—, —NR⁴(CO)NR⁴—,        -   and which is either not, once, twice or more than twice            interrupted by bivalent residues selected from the group            consisting of heterocyclo-diyl, heterocyclo-diylium⁺An⁻, and            C₆-C₁₄-aryldiyl,        -   and which is not, additionally or alternatively either once,            twice or more than twice substituted by substituents            selected from the group consisting of:        -   halogen, cyano, hydroxy, protected hydroxyl, C₆-C₁₄-aryl;            C₃-C₁₄-heterocyclyl, C₁-C₈-alkoxy, C₁-C₈-alkylthio,            C₂-C₈-alkenyl, —COOM, —SO₃M, —PO₃M₂, —SO₂N(R⁴)₂, —NR⁴SO₂R⁵,            —N(R⁴)₂—, —N⁺(R⁴)₃An⁻, —CO₂N(R⁴)₂, —COR⁴—, —OCOR⁵,            —O(CO)OR⁵, NR⁴(CO)R⁴, —NR⁴(CO)OR⁴, O(CO)N(R⁴)₂,            —NR⁴(CO)N(R⁴)₂,        -   whereby in case of m=2 the two substituents R² are different            or identical, or jointly are C₆-C₁₅-aryldiyl,            C₃-C₁₄-heterocyclo-diyl, C₁-C₁₈-alkanediyl,            C₂-C₁₈-alkenediyl or C₂-C₁₈-alkinediyl,    -   R³ independently denotes a substituent as defined for R¹ if n is        1,    -   whereby    -   R⁴ is independently selected from the group consisting of        hydrogen, C₁-C₈-alkyl, C₆-C₁₄-aryl and C₃-C₁₄-heterocyclyl or        N(R⁴)₂ as a whole is a N-containing C₃-C₁₄-heterocycle, or        N⁺(R⁴)₂An⁻ and N⁺(R⁴)₃An⁻ as a whole are or contain a        N-containing C₃-C₁₄-heterocyclyl substituent with a        counteranion,    -   R⁵ is independently selected from the group consisting of        C₁-C₈-alkyl, C₆-C₁₄-aryl and C₃-C₁₄-heterocyclyl or N(R⁵)₂ as a        whole is a N-containing C₃-C₁₄-heterocycle, or N⁺(R⁵)₂An⁻ and        N⁺(R⁵)₃An⁻ as a whole are or contain a N-containing        C₃-C₁₄-heterocyclyl substituent with a counteranion,    -   M is hydrogen, or 1/q equivalent of an q-valent metal ion or is        a C₃-C₁₄-heterocyclylium cation, an ammonium ion or a primary,        secondary, tertiary or quarternary organic ammonium ion or a        guanidinium ion or an organic guanidinium ion,    -   An⁻ is 1/p equivalent of a p-valent anion.

The compounds of formula (I) are known and can be prepared according toor in analogy to methods known to those skilled in the art.

For compounds wherein m is 1 or 2 preparation procedures are describedin WO 2005/014605, WO 2006/056541, WO 2006/074983 and in T. Ott,Dissertation ETH Zürich No. 18055, 2008, whereby the latter inparticular discloses compounds wherein R¹ is a polymeric backbone. Thesecompounds are incorporated herein by reference.

In an embodiment of the present invention, one or more photoinitiatorsof formula (I) are used, whereby in formula (I) X denotes oxygen.

In an embodiment of the present invention, one or more photoinitiatorsof formula (I) are used, whereby in formula (I) X denotes oxygen and nis 1 or 2.

In an embodiment of the present invention, one or more photoinitiatorsof formula (I) are used, whereby in formula (I) X denotes oxygen and nis 1 or 2 and m is 1 or 2.

In an embodiment of the present invention, one or more photoinitiatorsof formula (I) are used, whereby in formula (I):

-   -   X is oxygen    -   n is 1,    -   m is 0, 1 or 2,    -   R¹ is C₆-C₁₄-aryl or C₃-C₁₄-heterocyclyl, or        -   is C₁-C₁₈-alkyl or C₂-C₁₈-alkenyl,        -   which is either not or once, twice or more than twice            interrupted by non-successive functional groups selected            from the group consisting of:        -   —O—, —NR⁴—, —N⁺(R⁴)₂An⁻-, —CO—, —OCO—, NR⁴(CO)—, —(CO)NR⁴—,        -   and which is not, additionally or alternatively, for            example, alternatively either not, once, twice or more than            twice, for example, not or once, for example, once            substituted by substituents selected from the group            consisting of:        -   halogen, cyano, vicinal oxo (forming epoxides), vicinal NR⁵            (forming aziridins), C₆-C₁₄-aryl; C₁-C₈-alkoxy,            C₂-C₈-alkenyl, hydroxy, —SO₃M, —COOM, PO₃M₂, —PO(N(R⁵)₂)₂,            —SO₂N(R⁴)₂, —N(R⁴)₂, —N⁺(R⁴)₃An⁻,            C₃-C₁₄-heterocyclo-diylium⁺An⁻, —CO₂N(R⁴)₂, —COR⁴, —OCOR⁴,            NR⁴(CO)R⁵,    -   R² is C₆-C₁₄-aryl or C₃-C₁₄-heterocyclyl, or        -   is C₁-C₁₈-alkyl or C₂-C₁₈-alkenyl        -   which is either not, once, twice or more than twice            interrupted by non-successive functional groups selected            from the group consisting of:        -   —O—, —NR⁴—, —N⁺(R⁴)₂An⁻-, —CO—, NR⁴(CO)—, —NR⁴(CO)O—,            (CO)NR⁴—,        -   and which is not, additionally or alternatively either once,            twice or more than twice substituted by substituents            selected from the group consisting of:        -   halogen, cyano, hydroxyl, C₆-C₁₄-aryl; C₃-C₁₄-heterocyclyl,            C₁-C₈-alkylthio, C₂-C₈-alkenyl, —COOM, SO₂N(R⁴)₂—, N(R⁴)₂—,            —N⁺(R⁴)₃An⁻, —CO₂N(R⁴)₂,        -   whereby in case of m=2 the two substituents R² are different            or identical, or jointly are C₆-C₁₅-aryldiyl or            C₁-C₁₈-alkanediyl    -   R³ independently denotes a substituent as defined for R¹        directly above,    -   whereby,    -   R⁴ is independently selected from the group consisting of        halogen, C₁-C₈-alkyl, C₆-C₁₄-aryl and C₃-C₁₄-heterocyclyl or        N(R⁴)₂ as a whole is a N-containing C₃-C₁₄-heterocycle, or        N⁺(R⁴)₂An⁻ and N⁺(R⁴)₃An⁻ as a whole are or contain a        N-containing C₃-C₁₄-heterocyclyl substituent with a        counteranion,    -   R⁵ is independently selected from the group consisting        C₁-C₈-alkyl, C₆-C₁₄-aryl and C₃-C₁₄-heterocyclyl or N(R⁵)₂ as a        whole is a N-containing C₃-C₁₄-heterocycle, or N⁺(R⁵)₂An⁻ and        N⁺(R⁵)₃An⁻ as a whole are or contain a N-containing        C₃-C₁₄-heterocyclyl substituent with a counteranion,    -   M is hydrogen, or 1/q equivalent of an q-valent metal ion or is        a C₃-C₁₄-heterocyclylium cation, an ammonium ion or a primary,        secondary, tertiary or quarternary organic ammonium ion or a        guanidinium ion or an organic guanidinium ion, for example,        hydrogen, lithium, sodium, potassium, one half equivalent of        calcium, zinc or iron (II), or one third equivalent of        aluminium (III) or a C₃-C₁₄-heterocyclylium cation or an        ammonium ion or a primary, secondary, tertiary or quarternary        organic ammonium ion, and    -   An⁻ is 1/p equivalent of a p-valent anion.

In an embodiment of the present invention, one or more photoinitiatorsof formula (I) are used, where in formula (I):

-   -   X is oxygen    -   n is 1,    -   m is 1 or 2    -   R¹ and R³ are independently of each other,        -   C₆-C₁₄-aryl or C₃-C₁₄-heterocyclyl, or        -   are C₁-C₁₈-alkyl or C₂-C₁₈-alkenyl,        -   which is either not or once, twice or more than twice            interrupted by non-successive functional groups selected            from the group consisting of:        -   —O—, —NR⁴—, —NR⁴(CO)—, —(CO)NR⁴—,        -   and which is not, additionally or alternatively, for            example, alternatively either not, once, twice or more than            twice, for example, not or once, for example, once            substituted by substituents selected from the group            consisting of:        -   chloro, fluoro, cyano, hydroxy, C₆-C₁₄-aryl; C₁-C₈-alkoxy,            —SO₃M, —COOM, PO₃M₂, —PO(N(R⁵)₂)₂, —SO₂N(R⁴)₂, —N(R⁴)₂,            —N⁺(R⁴)₃An⁻, C₃-C₁₄-heterocyclo-diylium⁺An⁻, —CO₂N(R⁴)₂,            —COR⁴, —(CO)OR⁴, —OCOR⁴, NR⁴(CO)R⁵,    -   R² is C₆-C₁₄-aryl, whereby in case of m=2 the two substituents        R² are different or identical, for example, identical or jointly        are C₆-C₁₅-aryldiyl or C₁-C₁₈-alkanediyl, whereby R² is, for        example, C₆-C₁₄-aryl.    -   whereby,    -   R⁴ is independently selected from the group consisting of        hydrogen, C₁-C₈-alkyl, C₆-C₁₄-aryl and C₃-C₁₄-heterocyclyl or        N(R⁴)₂ as a whole is a N-containing C₃-C₁₄-heterocycle, or        N⁺(R⁴)₂An⁻ and N⁺(R⁴)₃An⁻ as a whole are or contain a        N-containing C₃-C₁₄-heterocyclyl substituent with a        counteranion,    -   R⁵ is independently selected from the group consisting        C₁-C₈-alkyl, C₆-C₁₄-aryl and C₃-C₁₄-heterocyclyl or N(R⁵)₂ as a        whole is a N-containing C₃-C₁₄-heterocycle, or N⁺(R⁵)₂An⁻ and        N⁺(R⁵)₃An⁻ as a whole are or contain a N-containing        C₃-C₁₄-heterocyclyl substituent with a counteranion,    -   M is hydrogen, or 1/q equivalent of an q-valent metal ion or is        a C₃-C₁₄-heterocyclylium cation, an ammonium ion or a primary,        secondary, tertiary or quarternary organic ammonium ion or a        guanidinium ion or an organic guanidinium ion, for example,        hydrogen, lithium, sodium, potassium, one half equivalent of        calcium, zinc or iron (II), or one third equivalent of        aluminum (III) or a C₃-C₁₄-heterocyclylium cation or an ammonium        ion or a primary, secondary, tertiary or quarternary organic        ammonium ion, for example, hydrogen, lithium, sodium and        potassium, and    -   An⁻ is 1/p equivalent of a p-valent anion, for example,        chloride, a carboxylate, C₁-C₈-alkylsulfate, C₆-C₁₄-arylsulfate,        hexafluorophosphate, tetrafluoroborate, dihydrogenphosphate, one        half equivalent of sulphate or hydrogenphosphate.

In an embodiment of the present invention, one or more photoinitiatorsof formula (I) are used, where in formula (I):

-   -   X is oxygen    -   n is 1,    -   m is 1 or 2,    -   R¹ and R³ are independently of each other C₆-C₁₄-aryl, or        -   are C₁-C₁₈-alkyl,        -   which is either not or once, twice or more than twice            interrupted by non-successive functional groups selected            from the group consisting of:        -   —O— or —NR⁴—,        -   and which is not, additionally or alternatively, for            example, alternatively either not, once, twice or more than            twice, for example, not or once, for example, once            substituted by substituents selected from the group            consisting of:        -   chloro, fluoro, C₁-C₈-alkoxy, hydroxy, —SO₃M, —COOM, PO₃M₂,            SO₂N(R⁴)₂, —N(R⁴)₂, —N⁺(R⁴)₃An⁻, —CO₂N(R⁴)₂,    -   R² is C₆-C₁₄-aryl,        -   whereby in case of m=2 the two substituents R² are different            or identical, for example, identical or jointly are            C₆-C₁₅-aryldiyl or C₁-C₁₈-alkanediyl, whereby, for example,            R² is C₆-C₁₄-aryl.    -   whereby,    -   R⁴ is independently selected from the group consisting of        C₁-C₈-alkyl, C₆-C₁₄-aryl and C₃-C₁₄-heterocyclyl or N(R⁴)₂ as a        whole is a N-containing C₃-C₁₄-heterocycle, or N⁺(R⁴)₂An⁻ and        N⁺(R⁴)₃An⁻ as a whole are or contain a N-containing        C₃-C₁₄-heterocyclyl substituent with a counteranion,    -   M is hydrogen, or 1/q equivalent of an q-valent metal ion or is        a C₃-C₁₄-heterocyclylium cation, an ammonium ion or a primary,        secondary, tertiary or quarternary organic ammonium ion or a        guanidinium ion or an organic guanidinium ion, for example,        hydrogen, lithium, sodium, potassium, one half equivalent of        calcium, zinc or iron (II), or one third equivalent of        aluminium (III) or a C₃-C₁₄-heterocyclylium cation or an        ammonium ion or a primary, secondary, tertiary or quarternary        organic ammonium ion, for example, lithium, sodium and        potassium, and fore example, hydrogen, lithium, sodium and        potassium, and    -   An⁻ is 1/p equivalent of a p-valent anion, for example,        chloride, a C₁-C₈-alkyl carboxylate, C₁-C₈-alkylsulfate,        C₆-C₁₄-arylsulfate, hexafluorophosphate, tetrafluoroborate,        dihydrogenphosphate, one half equivalent of sulphate or        hydrogenphosphate.

In an embodiment of the present invention, one or more photoinitiatorsof formula (I) are used, where in formula (I):

-   -   X is oxygen    -   n is 1,    -   m is 1 or 2,    -   R¹ and R³ are different or identical and are C₆-C₁₄-aryl, or        -   are C₁-C₁₈-alkyl,        -   which is either not or once, twice or more than twice            interrupted by non-successive functional groups selected            from the group consisting of:        -   —O—, —NR⁴—, for example, in case of —O— to form            polyethyleneglycolether groups [—CH₂CH₂—O]_(x)—H,            [—CH₂CH₂—O]_((x-1))—CH₃ or [—CH₂CH₂—O]_((x-1))—CH₂CH₃ with x            being an integer from 1 to 8,        -   and which additionally or alternatively are either not,            once, twice or more than twice, for example, not or once,            for example, once substituted by substituents selected from            the group consisting of: chloro, fluoro, hydroxy, —SO₃M,            —COOM, —CON(R⁴)₂, —N(R⁴)₂, —N⁺(R⁴)₃An⁻, heterocyclylium⁺An⁻,            for example, —COOM, for example, once by COOM, and    -   R² is C₆-C₁₄-aryl, for example, 2,4,6-trimethylphenyl (mesityl)        or 2,6-dimethoxyphenyl, whereby in case of m=2 the substituents        R² are different or identical, for example, identical, for        example, identically are 2,4,6-trimethylphenyl or        2,6-dimethoxyphenyl, for example, 2,4,6-trimethylphenyl,    -   whereby,    -   R⁴ is independently selected from the group consisting of        hydrogen, C₁-C₈-alkyl, C₆-C₁₄-aryl and C₃-C₁₄-heterocyclyl or        N(R⁴)₂ as a whole is a N-containing C₃-C₁₄-heterocycle, or        N⁺(R⁴)₂An⁻ and N⁺(R⁴)₃An⁻ as a whole are or contain a        N-containing C₃-C₁₄-heterocyclyl substituent with a        counteranion,    -   M is hydrogen, or 1/q equivalent of an q-valent metal ion or is        a C₃-C₁₄-heterocyclylium cation, an ammonium ion or a primary,        secondary, tertiary or quarternary organic ammonium ion or a        guanidinium ion or an organic guanidinium ion, for example,        hydrogen, lithium, sodium, potassium, one half equivalent of        calcium, zinc or iron (II), or one third equivalent of        aluminium (III) or a C₃-C₁₄-heterocyclylium cation or an        ammonium ion or a primary, secondary, tertiary or quarternary        organic ammonium ion, for example, hydrogen, lithium, sodium and        potassium, and    -   An⁻ is 1/p equivalent of a p-valent anion, for example,        chloride, a C₁-C₈-alkyl carboxylate, C₁-C₈-alkylsulfate,        C₆-C₁₄-arylsulfate, hexafluorophosphate, tetrafluoroborate,        dihydrogenphosphate, one half equivalent of sulphate or        hydrogenphosphate.

Examples of photoinitiators of formula (I) are:

2-(bis(2,4,6-trimethylbenzoyl)phosphoryl)acetic acid (hereinafter alsoreferred to as BAPO-AA) and its salts, in particular its sodium andpotassium salts,(2-(2-(2-methoxyethoxy)ethoxy)ethyl)-(bis(2,4,6-trimethylbenzoyl)-phosphineoxide,2,4,6-trimethylbenzoyl-diphenylphosphineoxide (hereinafter also referredto as MAPO, which is commercially available as Lucirin TPO from BASF SE)and bis(2,4,6-trimethylbenzoyl)-phenylphosphineoxide (which iscommercially available as Irgacure® 819 from BASF SE).

In an embodiment for the process according to the present invention,water-soluble photoinitiators of formula (I) are employed if apolymerization medium, in particular, a heterophase medium, comprisingan aqueous phase is used. As used herein “water-soluble” means asolubility of a photoinitiator in water at 25° C. of at least 0.5 g per1,000 g of water.

As used herein, and unless specifically stated otherwise, C₆-C₁₄-aryldenotes carbocyclic aromatic substituents having six to fourteen carbonatoms within the aromatic system as such, i.e., without carbon atoms ofsubstituents, for example, phenyl (C₆), naphthyl (C₁₀), phenanthrenyland anthracenyl (each C₁₄), whereby said carbocyclic, aromaticsubstituents are unsubstituted or substituted by up to five identical ordifferent substituents per cycle. The substituents can, for example, beselected from the group consisting of fluoro, bromo, chloro, iodo,nitro, cyano, formyl or protected formyl, hydroxyl or protectedhydroxyl, C₁-C₈-alkyl, C₁-C₈-haloalkyl, C₁-C₈-alkoxy, C₁-C₈-haloalkoxy,C₆-C₁₄-aryl, in particular phenyl and naphthyl, di(C₁-C₈-alkyl)amino,(C₁-C₈-alkyl)amino, CO(C₁-C₈-alkyl), OCO(C₁-C₈-alkyl),NHCO(C₁-C₈-alkyl), N(C₁-C₈-alkyl)CO(C₁-C₈-alkyl), CO(C₆-C₁₄-aryl),OCO(C₆-C₁₄-aryl), NHCO(C₆-C₁₄-aryl), N(C₁-C₈-alkyl)CO(C₆-C₁₄-aryl),COO—(C₁-C₈-alkyl), COO—(C₆-C₁₄-aryl), CON(C₁-C₈-alkyl)₂ orCONH(C₁-C₈-alkyl), CO₂M, CONH₂, SO₂NH₂, SO₂N(C₁-C₈-alkyl)₂, SO₃M andPO₃M₂.

In an embodiment of the present invention, the carbocyclic, aromaticsubstituents are unsubstituted or substituted by up to three identicalor different substituents per cycle selected from the group consistingof fluoro, chloro, cyano, C₁-C₈-alkyl, C₁-C₈-haloalkyl, C₁-C₈-alkoxy,C₁-C₈-haloalkoxy, C₆-C₁₄-aryl, in particular phenyl.

In an embodiment of the present invention, the carbocyclic, aromaticsubstituents are unsubstituted or substituted by up to three identicalor different substituents per cycle selected from the group consistingof fluorine, C₁-C₈-alkyl, C₁-C₈-perfluoroalkyl, C₁-C₈-alkoxy,C₁-C₈-perfluoroalkoxy, and phenyl.

Examples of carbocyclic, aromatic substituents are phenyl,2,4,6-trimethylphenyl and 2,6-dimethoxyphenyl.

The definitions given above including their areas of preference alsoapply analogously to C₆-C₁₄-aryl-diyl substituents.

As used herein and unless specifically stated otherwise,C₃-C₁₄-heterocyclyl denotes heterocyclic aliphatic, aromatic or mixedaliphatic and aromatic substituents in which no, one, two or threeskeleton atoms per cycle, but at least one skeleton atom in the entirecyclic system is a heteroatom selected from the group consisting ofnitrogen, sulphur and oxygen and whereby the entire cyclic system assuch, i.e., without carbon atoms of substituents, comprises three tofourteen carbon atoms and whereby the heterocyclic aliphatic, aromaticor mixed aliphatic and aromatic substituents are unsubstituted orsubstituted by up to five identical or different substituents per cycle,whereby the substituents are selected from the same group as given abovefor carbocyclic aromatic substituents including the areas of preference.

Examples of heterocyclyl-substituents are pyridinyl, oxazolyl,thiophen-yl, benzofuranyl, benzothiophen-yl, dibenzofuranyl,dibenzothiophenyl, furanyl, indolyl, pyridazinyl, pyrazinyl, imidazolyl,pyrimidinyl and quinolinyl, either unsubstituted or substituted with upto three substituents selected from the group consisting of fluorine,C₁-C₈-alkyl, C₁-C₈-perfluoroalkyl, C₁-C₈-alkoxy, C₁-C₈-perfluoroalkoxy,and phenyl.

The definitions given above, including the examples, also applyanalogously to C₃-C₁₄-heterocyclylium cations, the bivalentC₃-C₁₄-heterocyclo-diyl substituents and the bivalentC₃-C₁₄-heterocyclo-diylium cations.

Examples of C₃-C₁₄-heterocyclylium cations areN—(C₁-C₈-alkyl)imidazolium or pyridinium cations.

Examples of C₃-C₁₄-heterocyclo-diylium cations are N,N-imidazol-diyliumcations.

As used herein, and unless specifically stated otherwise, protectedformyl is a formyl substituent which is protected by conversion to anaminal, acetal or a mixed aminal acetal, whereby the aminals, acetalsand mixed aminal acetals are either acyclic or cyclic.

For example, protected formyl is 1,1-(2,4-dioxycyclopentanediyl).

As used herein, and unless specifically stated otherwise, protectedhydroxyl is a hydroxyl radical which is protected by conversion to aketal, acetal or a mixed aminal acetal, whereby the aminals, acetals andmixed aminal acetals are either acyclic or cyclic. A specific example ofprotected hydroxyl is tetrahydropyranyl (O-THP).

As used herein, and unless specifically stated otherwise, C₁-C₁₈-alkyl,C₁-C₁₈-alkanediyl, C₁-C₁₈-alkoxy, C₁-C₈-alkylthio, C₂-C₁₈-alkenyl,C₂-C₁₈-alkenediyl and C₁-C₁₈-alkinediyl are a straight-chain, cycliceither in part or as a whole, branched or unbranched alkyl, alkanediyl,alkoxy, alkylthio, alkenyl, alkenediyl and alkinediyl substituentshaving the given number of carbon atoms in the substituent as such,i.e., without carbon atoms of further, optionally present substituentsor carbon atoms of functions interrupting the aforementionedsubstituents. As an example, a benzyl substituent represents a C₁-alkylsubstituent substituted by phenyl.

The same analogously applies to C₁-C₈, C₁-C₂₄ and C₆-C₂₄-alkyl,C₂-C₁₈-alkanediyl, C₃-C₁₈-alkanetriyl C₄-C₁₈-alkanetetrayl,C₂-C₁₈-alkenediyl, C₃-C₁₈-alkenetriyl, C₄-C₁₈-alkenetetrayl andC₂-C₁₈-alkinediyl substituents.

Haloalkyl or haloalkoxy substituents denote alkyl or alkoxy substituentswith the given number of carbon atoms which are once or more than once,for example, fully substituted by halogen.

Fluoroalkyl or fluoroalkoxy substituents denote alkyl or alkoxysubstituents with the given number of carbon atoms which are once ormore than once, for example, fully substituted by fluorine.

Perfluoroalkyl or perfluoroalkoxy substituents denote alkyl or alkoxysubstituents with the given number of carbon atoms which are fullysubstituted by fluorine.

Specific examples of C₁-C₈-alkyl are methyl, ethyl, n-propyl, isopropyl,n-butyl, tert-butyl, n-pentyl, cyclohexyl, n-hexyl, n-heptyl, n-octyland isooctyl. Additional examples for C₁-C₁₈-alkyl are norbornyl,adamantyl, n-decyl, n-dodecyl alkyl, n-hexadecyl, n-octadecyl.

Specific examples of C₁-C₁₈-alkanediyl-substituents are methylene,1,1-ethylene, 1,2-ethylene, 1,1-propylene, 1,2-propylene, 1,3-propylene,1,1-butylene, 1,2-butylene, 2,3-butylene, 1,4-butylene, 1,5-pentylene,1,6-hexylene, 1,1-cyclohexylene, 1,4-cyclohexylene, 1,2-cyclohexyleneand 1,8-octylene.

Specific examples of C₁-C₈-alkoxy-substituents are methoxy, ethoxy,isopropoxy, n-propoxy, n-butoxy, tert-butoxy and cyclohexyloxy.

Specific examples of C₂-C₁₈-alkenyl-substituents are allyl, 3-propenyland buten-2-yl.

Specific examples of C₂-C₁₈-alkinyl-substituents are ethinyl, and1,3-propinyl.

Polymerizable Monomers

The polymerization medium, in particular the heterophase medium furthercomprises one or more polymerizable monomers.

As used herein, the term polymerizable monomer encompasses all monomerswhich can be polymerized in a radical polymerization.

Polymerizable monomers can, for example, be selected from the groupconsisting of those of formula (IIa):

wherein,

-   -   R⁶, R⁷, R⁸ and R⁹ are independently of one another selected from        the group consisting of:        -   hydrogen, cyano, fluorine, chlorine, bromine, iodine,            C₆-C₁₄-aryl, C₃-C₁₄-heterocyclyl, C₁-C₁₈-alkoxy,            C₁-C₁₈-alkyl, C₂-C₁₈-alkenyl and C₂-C₁₈-alkinyl,            -   which is either directly bound to the double bond                depicted in formula (IIa) or in case of C₆-C₁₄-aryl,                C₃-C₁₄-heterocyclyl, C₁-C₁₈-alkyl, C₂-C₁₈-alkenyl and                C₂-C₁₈-alkinyl alternatively via a functional group                selected from the group consisting of:            -   —CO—, —OCO—, —O(CO)O—, NR⁴(CO)—, —NR⁴(CO)O—, —O(CO)NR⁴—,                —(CO)NR⁴—, —NR⁴(CO)NR⁴—, —Si(R⁵)₂—, —OSi(R⁵)₂—,                —OSi(R⁵)₂O—, —Si(R⁵)₂O—,        -   and            -   which is either not, once, twice or more than twice,                interrupted by non-successive functional groups selected                from the group consisting of:            -   —O—, —CO—, —OCO—, —O(CO)O—, NR⁴(CO)—, —NR⁴(CO)O—,                —O(CO)NR⁴—, —(CO)NR⁴—, —NR⁴(CO)NR⁴—, —Si(R⁵)₂—,                —OSi(R⁵)₂—, —OSi(R⁵)₂O—, —Si(R⁵)₂O—,            -   and which is additionally or alternatively either not,                once, twice or more than twice, interrupted by bivalent                residues selected from the group consisting of                C₃-C₁₄-heterocyclo-diyl and C₆-C₁₄-aryldiyl,            -   and which is not, additionally or alternatively either                once, twice or more than twice substituted by                substituents selected from the group consisting of:            -   halogen, cyano, vicinal oxo (forming epoxides), vicinal                NR⁵ (forming aziridins), C₆-C₁₄-aryl;                C₃-C₁₄-heterocyclyl, C₁-C₈-alkylthio, hydroxy,                —SO₂N(R⁴)₂, NR⁴SO₂—R⁵, —N(R⁴)₂, —CO₂N(R⁴)₂, —COR⁴,                —OCOR⁴, —O(CO)OR⁴, NR⁴(CO)R⁵, —NR⁴(CO)OR⁵, O(CO)N(R⁴)₂,                —NR⁴(CO)N(R⁴)₂, —OSi(OR⁵)_(y-3)(R⁵)_(y),                —Si(OR⁵)_(y-3)(R⁵)_(y) where y is 1, 2 or 3.    -   or wherein,    -   two residues of R⁶, R⁷, R⁸ and R⁹ together are:        -   C₂-C₁₈-alkanediyl or C₃-C₁₈-alkenediyl.

Polymerizable monomers of formula (IIa) can, for example, be selectedfrom the group consisting of those wherein at two or three of thesubstituents R⁶, R⁷, R⁸ and R⁹ are hydrogen.

Examples of polymerizable monomers further include those of formula(IIb):

-   -   wherein,    -   R⁶, R⁷ and R⁸ have the same meaning given above for formula        (IIa),    -   or wherein,    -   two residues of R⁶, R⁷ and R⁸ together are:        -   C₂-C₁₈-alkanediyl or C₃-C₁₈-alkenediyl,    -   and wherein,    -   t is an integer from 2 to 4, and    -   Y is missing such that R¹⁰ is directly bound to the double bond        depicted in formula (IIb) or is —CO— or —(CO)O—,    -   R¹⁰ is a t-valent residue selected from the group consisting of        C₂-C₁₈-alkanediyl (t=2), C₃-C₁₈-alkanetriyl (t=3),        C₄-C₁₈-alkanetetrayl (t=4), C₂-C₁₈-alkenediyl (t=2),        C₃-C₁₈-alkenetriyl (t=3), C₄-C₁₈-alkenetetrayl (t=4),        C₂-C₁₈-alkinediyl (t=2), C₆-C₁₄-aryldiyl (t=2) and        C₃-C₁₄-heterocyclodiyl (t=2).

Polymerizable monomers of formula (IIb) can, for example, be selectedfrom the group consisting of those wherein at two or three of thesubstituents R⁶, R⁷, R⁸ and R⁹ are hydrogen.

Examples of polymerizable monomers include:

Monoolefins such as:

-   -   Acrylic acid and methacrylic acid and their respective esters,        amides and nitriles, such as methyl-, ethyl-, n-butyl-,        glycidyl-, 2-ethylhexyl- and 2-hydroxyethyl acrylate,        acrylamide, N-isopropylacrylamide and acrylonitrile, and        methyl-, ethyl-, n-butyl-, glycidyl-, 2-ethylhexyl-,        2-hydroxyethyl and isobornyl methacrylate; methacrylamide,        N-isopropylmethacrylamide and methacrylonitrile;    -   other unsaturated carboxylic acids and their respective esters        such crotonic acid, maleic acid, fumaric acid, itaconic acid,        cinnamic acid and unsaturated fatty acids such as linolenic acid        or oleic acid and the respective C₁-C₈-alkyl esters of the        aforementioned acids and where applicable C₁-C₈-alkyl diesters;    -   vinyl ethers, such as ethyl vinyl ether and isobutyl vinyl        ether;    -   vinyl esters, such as vinyl acetate;    -   vinyl aromatic compounds such as vinylpyridine, styrene and        styrene substituted by C₁-C₈-alkyl- or halogen or sulfonic acid        salts at the aromatic ring, for example, styrene, 2-, 3- and        4-methylstyrene, 2-, 3- and 4-bromomethylstyrene, 2-, 3- and        4-chlorostyrene and p-methoxystyrene; and    -   siloxanes such as trimethoxyvinylsilane, triethoxyvinylsilane,

and multiolefins such as:

-   -   poly(meth)acrylates such as ethylene glycol diacrylate,        1,6-hexanediol diacrylate, propylene glycol diacrylate,        dipropylene glycol diacrylate, tripropylene glycol diacrylate,        neopentyl glycol diacrylate, hexamethylene glycol diacrylate and        bis-phenol-A diacrylate,        4,4′-bis(2-acryloyloxyethoxy)diphenylpropane, trimethylolpropane        tri-acrylate, pentaerythritol triacrylate, pentaerythritol        tetraacrylate, vinyl acrylate, polyethyleneglycol-mono-acrylate,        polyethylene-glycol-di-acrylate, ethylene glycol dimethacrylate,        1,6-hexanediol dimethacrylate, propylene glycol dimethacrylate,        dipropylene glycol dimethacrylate, tripropylene glycol        dimethacrylate, neopentyl glycol dimethacrylate, hexamethylene        glycol dimethacrylate and bis-phenol-A dimethacrylate,        4,4′-bis(2-methacryloyloxyethoxy)diphenylpropane,        trimethylolpropane tri-methacrylate, pentaerythritol        trimethacrylate, pentaerythritol tetramethacrylate, vinyl        methacrylate, polyethyleneglycol-mono-methacrylate,        polyethylene-glycol-di-methacrylate;    -   other multiolefins such as butadiene, isoprene, chloroprene,        2,4-dimethylbutadiene, cyclopentadiene, methylcyclopentadiene,        cyclohexadiene, divinyl-benzene, 1-vinyl-cyclohexadiene,        norbornadiene, 2-isopropenylnorbornene, 2-vinyl-norbornene,        diisopropenylbenzene, divinyltoluene, divinylxylene and C₁ to        C₂₀ alkyl-substituted derivatives of the aforementioned        divinylaromatic multiolefins, divinyl succinate, diallyl        phthalate, triallyl phosphate, triallyl isocyanurate,        tris-(hydroxyethyl)isocyanurate triacrylate (Sartomer 368; from        Cray Valley) and tris(2-acryloyl-ethyl)isocyanurate,        ethyleneglycoldivinylether, diethyleneglycoldivinylether,        triethylene-glycoldivinylether;

and any mixture of the aforementioned monoolefins and/or multiolefins.

In an embodiment of the present invention, monoolefins or mixtures ofmonoolefins of formula (IIa), for example, those monoolefins explicitlymentioned above are used, whereby butadiene, isoprene, chloroprene,methyl-, ethyl-, n-butyl- and 2-ethylhexylacrylate and methyl-, ethyl-,n-butyl- and 2-ethylhexylmethacrylate, acrylamide, acrylonitrile,vinylpyridine, styrene and styrene substituted by C₁-C₈-alkyl- orhalogen or sulfonic acid salts at the aromatic ring, for example,styrene, 2-, 3- and 4-methylstyrene, 2-, 3- and 4-bromomethylstyrene,2-, 3- and 4-chlorostyrene and p-methoxystyrene and any mixture of theaforementioned monoolefins.

In an embodiment of the present invention, where an aqueous phase isemployed in step A) and B), in particular as dispersed phase orcontinuous phase, in a heterophase polymerization, the polymerizablemonomer or the mixture of polymerizable monomers is used in an amountthat the content of the polymerizable monomer or the mixture ofpolymerizable monomers dissolved in the said aqueous phase is less than50 g/l, for example, less than 25 g/l, for example, less than 10 g/land, for example, less than 2 g/l.

In an embodiment of the present invention, the polymerizable monomer orthe mixture of polymerizable monomers is selected from those resultingin polymer nanoparticles having a glass transition temperature or amelting point or melting range higher than the polymerizationtemperature. This helps to avoid immediate agglomeration.

The weight ratio of photoinitiator to polymerizable monomer in theheterophase medium is typically of from 1:1 to 1:100,000, for example,between 1:5 and 1:100,000, for example, between 1:10 and 1:10,000 and,for example, 1:50 to 1:2,000.

In an embodiment of the present invention, the heterophase mediumcomprises a continuous aqueous phase and a dispersed organic phase,whereby the organic phase comprises the one or more polymerizablemonomers.

In an embodiment of the present invention, if heterophase polymerizationis applied in step B), the heterophase medium comprises a continuousaqueous phase and a dispersed organic phase, whereby the content ofpolymerizable monomer within the dispersed organic phase is 20 to 100wt.-%, for example, 90 to 100 wt.-% and, for example, 98 to 100 wt.-% ofone or more polymerizable monomers, whereby surfactants are not countedas being part of the organic phase.

Generally, in step A), the photoinitiator may be either added partiallyor completely. If in step A) the photoinitiator is added partially, therest can be added during step B) either batchwise or continuously.

The Polymerization Conditions

In step B), the one or more polymerizable monomers present in thepolymerization medium, in particular, in the heterophase medium arepolymerized by irradiating said polymerization medium, in particular, inthe heterophase medium, with electromagnetic radiation having awavelength sufficient to induce the generation of radicals.

This includes wavelengths sufficient to induce the generation ofradicals from:

-   -   at least the one or more photoinitiators employed and        optionally;    -   at least one reaction product of radicals generated from said        one or more photoinitiators with said one or more polymerizable        monomers, for example, at least one reaction product of radicals        comprising at least one phosphorous oxide (P═O) or phosphorous        sulfide (P═S) group with said one or more polymerizable        monomers; or    -   from both of the aforementioned sources of radicals.

It is apparent to those skilled in the art that the electromagneticradiation sufficient to induce the generation of radicals is dependenton the exact structure of the photoinitiator and/or the reaction productof radicals generated from the photoinitiator with the polymerizablemonomers but can be determined by performing a few, commonly knownsimple measurements, tests or experiments.

Such tests include UV-Vis spectroscopy and radical scavenger experimentsknown to those skilled in the art.

As a consequence, and in order to carry out the process according to thepresent invention, one may either adapt the photoinitiators employed toa given source of electromagnetic radiation or vice versa.

With the photoinitiators used herein generation of radicals of any typementioned above is typically induced by irradiation with electromagneticradiation having a wavelength of below 500 nm, for example, below 480nm, for example, in the range of 200 to 480 nm, for example, in therange of 280 to 480 nm.

Suitable sources of electromagnetic radiation having a wavelengthsufficient to induce the generation of radicals include eximer laserssuch as KrF and XeF-lasers; UV lamps like low-pressure, medium-pressure,high-pressure and super-high-pressure mercury lamps which can be undopedor doped, for example: with gallium iodide, thallium iodide or othermetal halides; blue, violet-blue or UV-LEDs; concentrated, direct orindirect sunlight; xenon or xenon mercury arc lamps such ascontinuous-output xenon short- or long-arc lamps, flash lamps such asxenon or xenon mercury flash lamps; microwave-excited metal vapourlamps; excimer lamps, superactinic fluorescent tubes; fluorescent lamps;and noble gas incandescent lamps.

Examples of sources are UV lamps like low-pressure, medium-pressure,high-pressure and super-high-pressure mercury lamps which can be undopedor doped, for example, with gallium iodide, thallium iodide or othermetal halides; blue, violet-blue or UV-LEDs, xenon or xenon mercury arclamps such as continuous-output xenon short- or long-arc lamps.

In an embodiment of the present invention, multichromatic sources ofelectromagnetic radiation are used to generate radicals.

As used herein a multichromatic sources of electromagnetic radiationdenotes a source emitting electromagnetic radiation having more than onerelative emission maxima (also known as emission bands), for example,more than one relative emission maxima within the wavelength rangesdisclosed above.

The irradiation time of the polymerization medium, in particular, theheterophase medium may vary depending on the intensity of irradiance andits penetration depth within the polymerization medium, in particular,the heterophase medium, but typically is for example in the range offrom 5 min to 24 h.

In an embodiment of the present invention, irradiation of thepolymerization medium, in particular, the heterophase medium, iseffected in such a manner that the ratio of the irradiated surface ofthe polymerization medium, in particular, the heterophase medium and itsvolume (SVR) is at least 200 m⁻¹, for example, at least 600 m⁻¹, forexample, at least 1000 m⁻¹, for example, at least 1500 m⁻1.

FIGS. 1, 2 and 3 depict the examples given below, which are not intendedto limit the spatial design of devices allowing the described SVR.

A ratio of the irradiated surface of the polymerization medium (PM), inparticular, the heterophase medium (HM) and its volume of at least 200m⁻¹ is, for example, achieved by irradiation of the surface (S) a of athin film of polymerization medium, in particular, the heterophasemedium (HM) having a uniform layer thickness (L) of 5 mm (see FIG. 1).

A ratio of the irradiated surface of the polymerization medium, inparticular, the heterophase medium and its volume of at least 200 m⁻¹is, for example, also achieved by irradiation of the surface a of apolymerization medium (PM), in particular, the heterophase medium (HM)confined

-   -   in a transparent round tube having an inner radius (r) of 5 mm        if irradiated from one direction (in this case the irradiated        surface S is π·r·l, the volume π·r²·l with l being the length of        the irradiated tube or the irradiated part thereof) (see FIG. 2        in which the dashed part of the surface is not irradiated), or    -   in a transparent round tube having a inner radius (r) of 10 mm        if irradiated from two opposite directions (in this case the        irradiated surface is the whole inner surface of 2π·r·l, the        volume is π·r²·l with l being the length of the irradiated tube        or the irradiated part thereof) (see FIG. 3).

It was surprisingly found that irradiation in the spatial dimensionsdescribed above significantly increases polymerization rates and, whereheterophase polymerization is applied, also molecular weights of thepolymer chains within the lattices.

In an embodiment of the present invention, in particular, whereheterophase polymerization is applied, the irradiation is effected in atransparent tube, tubing or channel having an effective diameter of 5 mmor less, for example, 0.1 to 5 mm, for example, 2 mm or less, forexample, 0.1 to 2 mm, for example, 1 mm or less, and for example, 0.1 to1 mm.

As used herein, the effective diameter of a tube, tubing or channel,which is typically circular, but also might deviate from circular shape,is understood as the diameter of a circular tube, tubing or channelhaving the same cross sectional area.

In an embodiment of the present invention, in particular, where bulk orsolution polymerization, for example, bulk polymerization is applied,the irradiation is effected by irradiating a thin film of polymerizationmedium having a layer thickness of 5 mm or less, for example 0.001 to 5mm, for example, 2 mm or less, for example, 0.001 to 2 mm and more, forexample, 1 mm or less, for example, 0.001 to 1 mm. Low layer thicknessescan, for example, be achieved by spin coating.

In an embodiment of the present invention, the irradiation time of thepolymerization medium, in particular, the heterophase medium, istherefore typically, for example, in the range of from 1 s to 30 min,for example, from 5 s to 15 min, and, for example, from 10 s to 3 min.Longer exposure times than 30 min typically do not positively affect themonomer conversion.

In an embodiment of the present invention, the irradiance withelectromagnetic radiation sufficient to induce the generation ofradicals is effected at average intensities of at least 50 W per squaremeter of irradiated surface of the polymerization medium, in particular,the heterophase medium (50 W/m²), for example, at least 100 W/m², forexample, from 200 W/m² to 50 kW/m² and, for example, from 200 W/m² to 10kW/m².

In an embodiment of the present invention, irradiance is effected withelectromagnetic radiation having a wavelength of below 500 nm at averageintensities of at least 50 W per square meter of irradiated surface ofthe polymerization medium, in particular, the heterophase medium (50W/m²), for example, at least 100 W/m², for example, from 200 W/m² to 50kW/m² and, for example, from 200 W/m² to 10 kW/m². In an embodiment, theSVR is, for example, at least 600 m⁻¹, for example, at least 1000 m⁻¹,and, for example, at least 1500 m¹.

In an embodiment of the present invention, irradiance is effected withelectromagnetic radiation having a wavelength of below 480 nm at averageintensities of at least 50 W per square meter of irradiated surface ofthe polymerization medium, in particular, the heterophase medium (50W/m²), for example, at least 100 W/m², for example, from 200 W/m² to 50kW/m² and, for example, from 200 W/m² to 10 kW/m². In an embodiment, theSVR can, for example, be at least 600 m⁻¹, for example, at least 1000m⁻¹, and, for example, at least 1500 m⁻¹.

In an embodiment of the present invention, irradiance is effected withelectromagnetic radiation having a wavelength in the range of 280 to 480nm at average intensities of at least 200 W per square meter ofirradiated surface of the polymerization medium, in particular, theheterophase medium (50 W/m²), for example, at least 100 W/m² forexample, from 200 W/m² to 50 kW/m² and, for example, from 200 W/m² to 10kW/m². In an embodiment, the SVR can, for example, be at least 600 m⁻¹,for example, at least 1000 m⁻¹, and, for example, at least 1500 m⁻1.

In an embodiment of the present invention, step B) is carried out with

-   -   a SVR of at least 600 m⁻¹, for example, at least 1000 m⁻¹, and,        for example, at least 1500 m⁻¹    -   an irradiance with electromagnetic radiation having a wavelength        of below 500 nm at average intensities of at least 50 W per        square meter of irradiated surface of the polymerization medium,        in particular, the heterophase medium (50 W/m²), for example, at        least 100 W/m², for example, from 200 W/m² to 50 kW/m² and, for        example, from 200 W/m² to 10 kW/m²    -   for 1 s to 30 min, for example, from 5 s to 15 min and, for        example, from 10 s to 3 min.

In an embodiment of the present invention, step B) is carried out with

-   -   a SVR of at least 1000 m⁻¹, for example, at least 1500 m⁻¹    -   an irradiance with electromagnetic radiation having a wavelength        of below 480 nm at average intensities of at least 50 W per        square meter of irradiated surface of the polymerization medium,        in particular, the heterophase medium (50 W/m²), for example, at        least 100 W/m², for example, from 200 W/m² to 50 kW/m² and, for        example, from 200 W/m² to 10 kW/m²    -   for 5 s to 15 min, for example, from 10 s to 3 min.

In an embodiment of the present invention, step B) is carried out with

-   -   a SVR of at least 1000 m⁻¹, for example, 1500 m⁻¹    -   an irradiance with electromagnetic radiation having a wavelength        in the range of 280 to 480 nm at average intensities of at least        50 W per square meter of irradiated surface of the        polymerization medium, in particular, the heterophase medium (50        W/m²), for example, at least 100 W/m², for example, 200 W/m² to        50 kW/m² and, for example, from 200 W/m² to 10 kW/m²    -   for 5 s to 15 min, for example, from 10 s to 3 min.

The determination of a suitable reaction temperature range duringpolymerization depends on the composition of the polymerization medium,for example, where a heterophase medium is employed on the compositionof the continuous phase, the composition of the dispersed phase and thereaction pressure since freezing or boiling in the polymerization mediumshould be avoided, in particular, when the continuous phase or thedispersed phase is an aqueous phase within a heterophase medium.

Generally, a typical reaction temperature range to carry out thepolymerization according to step B) is from −30° C. to 120° C., forexample, from −10 to 80° C. and, for example, from 0 to 50° C.

A typical reaction pressure range to carry out the polymerizationaccording to step B) is from 100 hPa to 10 MPa, for example, from 500hPa to 1 MPa.

In an embodiment of the present invention, the polymerization carriedout such that a monomer conversion of 60 to 100 wt-% of thepolymerizable monomers is achieved, for example, 90 to 100 wt.-%.

Step B) can be carried out batchwise or continuously, whereby step B)is, for example, carried out continuously using a flow-through reactorif a heterophase medium is applied.

In those embodiments where a flow-through reactor is employed, the flowrate is adjusted to an average flow velocity of 0.005 to 1 m/s, forexample, 0.01 to 0.5 m/s.

In an embodiment of the present invention, where a heterophase medium isemployed, the lattices comprise 0.001 to 50 wt-%, for example, 0.001 to25 wt-% and, for example, 0.5 to 20 wt-% of the aforementioned polymernanoparticles.

The molecular weight of the polymer chains within the polymernanoparticles typically have a weight average molecular mass of morethan 500 kg/mol to 5,000 kg/mol, for example, 1,000 kg/mol to 5,000kg/mol.

The average particle sizes experimentally obtained are typically in therange of from 30 to 150 nm as measured by Dynamic Light Scattering (DLS)using a Nicomp particle sizer (PSS Santa Barbara, USA, model 370) at afixed scattering angle of 90°.

The lattices comprising polymer nanoparticles obtained typically have anM-PDI of 1.1 to 20, for example, an M-PDI of 2 to 10.

The lattices comprising polymer nanoparticles further typically have avery low DLS-PDI of 0.05 to 0.40, for example, a DLS-PDI of 0.08 to0.20. Step C) might directly be carried out after performance of stepB).

In an embodiment of the present invention, residual polymerizablemonomers, if present at all (see above), are removed from the resultingpolymer or dispersion by standard stripping or distillation techniques.

In an embodiment of the present invention, in particular, where solutionor heterophase polymerization was applied in step B), the polymer orpolymer nanoparticles can be concentrated in or isolated from thepolymerized medium or the lattices using standard techniques well knownto those skilled in the art and subsequently directly or afterre-dispersion employed in step C).

Where solution or bulk polymerization was applied in step B), thepreparation of modified nanoparticles can be effected by first preparinga solution of the polymer or taking the solution obtained via solutionpolymerization and adding the solution to a solvent or a solvent to thepolymer solution, wherein the solvent or the polymer is only sparinglysoluble which leads in a manner known per se to formation of lattices,in particular, if additional surfactants and/or high shear forces areapplied. The original solvent of the polymer solution can, for example,be removed via standard techniques such as distillation.

In an embodiment of the present invention, the polymer obtained in stepB) is purified before its employment in step C). The purification can beeffected, for example, by precipitation, dialysis or any other mannerknown to those skilled in the art.

To concentrate or isolate the polymer nanoparticles, inorganic salts orsolutions thereof are, for example, added to the suspension and theresulting mixture is subjected to centrifugation, sedimentation,filtration or other separation processes of a like nature.

In an embodiment of the present invention, the concentration orisolation is performed by nano- or microfiltration using membranes.

In step C), the polymers, in particular, the lattices or polymernanoparticles obtained in step B), are modified by irradiating saidpolymers, in particular, the lattices or polymer nanoparticles, withelectromagnetic radiation having a wavelength sufficient to induce thegeneration of radicals from said polymers and, in particular, from saidlattices or polymer nanoparticles in the presence of at least onemodifying agent.

Surprisingly, said modification does not require additionalphotoinitiators, for example, those of formula (I) or additionalphotoinitiators known to those skilled in the art since the polymers, inparticular, the lattices and the polymer nanoparticles, obtainedaccording in step B) were found to act as photoinitiators themselves.Therefore, in an embodiment, step C) is carried out without additionalphotoinitiators, in particular, without additional photoinitiators offormula (I) and, in an embodiment, in absence of photoinitiators offormula (I).

As used herein a modifying agent is any compound that is able to reactwith radicals generated by irradiation of the polymers, in particular,of the lattices or polymer nanoparticles obtained in step B).

In an embodiment of the present invention, polymerizable monomers asdefined above are used as modifying agents, whereby, for example, thepolymerizable monomers used in step C) are different from those taken instep A) and B).

If monoolefins or conjugated diolefins are employed as polymerizablemonomers in step C) block copolymers are obtained.

If multiolefins, in particular, non-conjugated crosslinkers are employedas polymerizable monomers in step C), crosslinked polymers are obtained.

If mono- or multiolefins carrying functional groups are employedtelechelic polymers or functionalized block copolymers can be obtained.

Examples of such mono- or multiolefins carrying functional groupsinclude

-   -   hydroxyfunctionalized (meth)acrylates such as        3-hydroxypropyl(meth)acrylate,        3,4-dihydroxybutylmono(meth)acrylatd,        2-hydroxyethyl(meth)acrylat, 4-Hydroxybutyl(meth)acrylat,        2-Hydroxypropylmeth)acrylat and        2,5-dimethyl-1,6-hexandiolmono(meth)acrylate.    -   aminofunctionalized (meth)acrylates such as        2-dimethylaminoethyl-(meth)acrylate (DMAEMA),        2-diethylaminoethyl-(meth)acrylate (DEAEMA),        2-tert-butylaminoethyl-(meth)acrylate (t-BAEMA),        2-dimethylaminoethyl-acrylate (DMAEA),        2-diethylaminoethyl-acrylate (DEAEA),        2-tert-butylaminoethyl-acrylate (t-BAEA),        3-dimethylaminopropyl-methacrylamide (DMAPMA) and        3-dimethylaminopropyl-acrylamide (DMAPA)    -   unsaturated functionalized (meth)acrylates such as        allyl(meth)acrylate    -   epoxy functionalized (meth)acrylates such as        glycidyl(meth)acrylate.    -   carboxylic acid functionalized (meth)acrylates such as        tert-butyl(meth)acrylate which may be subjected to        saponification or thermal degradation to obtain carboxylic acid        groups    -   silicon functionalized (meth)acrylates such as        3-methacryloxypropyltrimethoxysilane.

In an embodiment of the present invention, radical scavengers are usedas modifying agents. In this case, chain degradation occurs which lowersthe average molecular weight of the polymer, in particular, of thelatex.

For the irradiation in step C), the same conditions may be applied inany aspect as described for step B).

Step C) may be repeated once or more for example to obtain tri- ormultiblock copolymers if different monoolefins or conjugated diolefinsare employed as polymerizable monomers in every repeat of step C).

Mechanistic Aspects

In order to provide a better understanding of the present invention,some mechanistic aspects are discussed, which, however, shall in no waybe binding or be deemed a limiting feature.

The mechanism of classical photoinitiated polymerizations, inparticular, heterophase polymerizations such as aqueous emulsionpolymerization is rather well understood. The parameters that influencethe reaction have been determined, including the relative influences ofmonomer, initiator, temperature and reaction time on the resultingpolymer molecular weight and other features.

Upon exposure to electromagnetic radiation, the photoinitiators usedherein undergo exitation to the singlet state, electron-spin reversal tothe triplet state and fragmentation thereby forming at least tworadicals.

A possible explanation for generation of radicals in step B) or C), inparticular, the avalanche-like generation of radicals when using highSVRs, is given below using a photoinitiator of the bisacylphosphineoxide (BAPO) type as an example:B—(P═O)—B+hν→R.+.(P═O)—B  (A)B—(P═O)—B+hν→R.+.(P═O).+R′.  (B)

Residues B denote two acyl substituents of the photoinitiator, the thirdsubstituent was omitted for clarity. Radical formation and reaction may,depending on its nature, however, occur in the same manner as discussedfor B.

“hν” denotes electromagnetic radiation having a wavelength sufficient toinduce the generation of the radicals depicted in the respectiveformulae.

After initial fragmentation of the photoinitiator, the polymerization isthen started and propagated by reaction of the radicals formed accordingto equations (A) and (B) with n molecules of polymerizable monomer M.B.+nM→B-(M)_(n).  (C).(P═O)—B+nM→.(M)_(n)(P═O)—B  (D).(P═O).+nM→.(M)_(m)(P═O)-(M)_(p).  (E)(with m+p=n)

Termination occurs inter alia by radical combinations which limit therate of conversion by lowering the number of free radicals present inthe reaction mixture. Such termination reactions by radical combinationinclude, for example:B-(M)_(n1).+B-(M)_(n2).→B-(M)_(n1)-(M)_(n2)-B  (F)B-(M)_(n1).+.(M)_(n2)(P═O)—B→B(M)_(n1)-(M)_(n2)(P═O)—B  (G)B-(M)_(n).+.(M)_(m)(P═O)-(M)_(p).→B-(M)_(n)-(M)_(m)(P═O)-(M)_(p).  (H).(M)_(m1)(P═O)-(M)_(p1).+.(M)_(m1)(P═O)-(M)_(p1).→.(M)_(m1)(P═O)-(M)_(p1)-(M)_(m1)(P═O)-(M)_(p1).  (J)

According to equations (E), (H) and (J), incorporation of a phosphineoxide containing moiety into the growing polymer chain occurs.

The polymers formed according to equations (D) and (G) under irradiationcan undergo further scission of an acyl substituent resulting in theformation of further radicals:.(M)_(n)(P═O)—B+hν→.(M)_(n)(P═O).+B.  (K)B-(M)_(n1)-(M)_(n2)(P═O)—B+hν→B-(M)_(n1)-(M)_(n2)(P═O).+B.  (L)

Under the irradiation conditions with high SVRs, the dramatic increasein reaction rate is proposed to be caused by further fast fragmentationof polymer chains resulting, for example, from reactions according toequations (E), (H) and (J):.(M)_(m)(P═O)-(M)_(p) .+hν→.(M)_(m).+.(P═O)-(M)_(p).  (M)B-(M)_(n)-(M)_(m)(P═O)-(M)_(p) .+hν→B-(M)_(n)-(M)_(m)(P═O).+.(M)_(p). orB-(M)_(n)-(M)_(m).+.(P═O)⁻(M)_(p). orB-(M)_(n)-(M)_(m).+.(P═O).+.(M)_(p).  (N)(M)_(m1)(P═O)-(M)_(p1)-(M)_(m1)(P═O)-(M)_(p1) .hν→.(M)_(m1).+.(P═O)-(M)_(p1)-(M)_(m1)(P═O)-(M)_(p1)..(M)_(m1)(P═O).+.(M)_(p1)-(M)_(m1)(P═O)-(M)_(p1)..(M)_(m1)(P═O)-(M)_(p1)-(M)_(m1).+.(P═O)-(M)_(p1)..(M)_(m1)(P═O)-(M)_(p1)-(M)_(m1)-(P═O).+.(M)_(p1).etc.  (P)

The radicals so generated may further react with monomers M in analogyto the propagation reactions depicted in equations (C), (D) and (E).

For heterophase polymerizations, a commonly used descriptor of radicalheterophase polymerization is the average number of radicals perparticle ( n). This value depends on particle size and concentration,the rates of initiator decomposition, and radical entry into and exitout of particles. Classical emulsion polymerization of polystyrene andother polymers for example produces particles of less than 100 nmdiameter, each of which contain, on average, one half radical perparticle ( n=0.5). Such reactions are said to conform to so-calledzero-one kinetics, where each particle contains either one or no growingradical (see Ugelstad, J., Mork, P. C. & Aasen, J. O. Kinetics ofEmulsion Polymerization. J. Polym. Sci., A: Pol. Chem. 5, 2281-2288(1967)). As will be shown in the examples, the repeated chain scissionand avalanche-like radical generation discussed above leads to averagenumber of radicals per particle ( n) of up to 30, which explains theultra-fast reaction rates and high molecular weights observed.

In an embodiment of the present invention, therefore, the generation ofradicals of at least one reaction product of radicals generated from theone or more photoinitiators with the one or more polymerizable monomersoccurs via scission of a phosphorous-carbon-bond of reaction productscomprising a phosphorous oxide (P═O) or phosphorous sulphide (P═S)group.

In case photoinitiators of formula (I) are employed in which m is 1 or2, and in particular 2, the radical generation of at least one reactionproduct of said radicals with said one or more polymerizable monomersis, for example, meant to denote a radical generation other than byscission of a phosphorous-carbon bond between the (X═P) and the (C═O)—R²group.

In step C), the polymer chains finally formed in step B) are underirradiation fragmented again to form radicals as for example shown inequation (Q):B-(M)_(p)-(P═O)-(M)_(q)-B+hν→B-(M)_(p).+.(P═O)-(M)_(q)-BB-(M)_(p)-(P═O).+.(M)_(q)-B  (Q)

In the presence of a modifying agent representing, for example, afurther monomer, block copolymers are formed:B-(M)_(p)-(P═O).+nA→B-(M)_(p)-(P═O)-(A)_(n).  (R).(M)_(q)-B+nA→.(A)_(n)-(M)_(q)-B  (S)

Analogously, crosslinked polymers are obtainable if the modifying agentis a crosslinker, chain fragmentation is effected if the modifying agentis a radical scavenger.

Devices Suitable to Perform Steps B) and C)

The process can be carried out using every type of device designed tocarry out step B) and/or step C) and optionally also step A) under theconditions described hereinabove.

This includes photoreactors known to those skilled in the art havingirradiation zones and, in particular, those with dimensions to allowirradiation in with the prescribed SVR.

Suitable types of photoreactors include rising or falling filmphotoreactors and flow-through reactors, in particular, microfluidicdevices, in particular, if solution polymerization or heterophasepolymerization is applied.

Bulk polymerizations are typically performed batchwise. Flow-throughreactors may be any device comprising in flow direction an inlet, atleast one irradiation zone comprising a wall material transparent to theelectromagnetic radiation employed such as simple tubes, tubings orhoses and an outlet as well as means to convey the polymerizationmedium, in particular, the heterophase medium form the inlet via the atleast one exposure zone to the outlet such as pumps. In particular, theat least one irradiation zone has a SVR of 200 m⁻1, for example, atleast 600 m⁻¹, for example, at least 1000 m⁻¹ and, for example, at least1500 m⁻¹.

Suitable wall material transparent to the electromagnetic radiationgenerating radicals include polyolefins such as fluorinated polyolefinssuch as fluorinated poly(ethylene-co-propylene), hereinafter alsodenoted as FEP, and polytetrafluoroethylene, polyesters (includingpolycarbonates), polyacrylates, polyurethanes and glass such as quartzglass, borax containing glasses and other glasses which are at leastpartially transparent to the electromagnetic radiation employed.

Examples of suitable flow-through reactors include the flow-throughreactors described in US2008/013537, US2003/0118486 and US2003/0042126.

In an embodiment of the present invention, the flow-through reactorsfurther comprise at least one mixing device to carry out step A) whichis in flow direction arranged before the at least one exposure zone.

Said mixing zones may be equipped with the standard mixing elementsmentioned above. In an embodiment of the present invention, the mixingzone comprises static mixing elements such as slit type mixers.

FIGS. 4 and 5 further illustrate suitable devices to carry out thepresent invention.

FIG. 4 is an exemplary, simplified flow diagram of a process accordingto the present invention using a flow through reactor 1.

The feeding system comprises a storage tank 2 a for the monomers to bepolymerized and a storage tank 2 b for water W, surfactant SUR andphotoinitiator PI. Feed stream controller comprising conveying means 3 aand 3 b are employed to feed the monomers M, water W, surfactant SUR andphotoinitiator PI via lines 4 a and 4 b through a mixing device 5 toform a heterophase medium HM. The heterophase medium HM is then fed viafeed line 6 further to irradiation zone 7 which is irradiated by asource of electromagnetic radiation 8 powered by power source 9 andshielded by a filter 10 through the UV transparent wall material 11.Cooling of the heterophase medium HM is effected by cooling means 12After leaving the exposure zone 7 the resulting latex comprising polymernanoparticles L is transferred via exit line 13 to collection tank 14for further workup or storage.

FIG. 5 is an exemplary, detailed cross sectional view of a flow-throughreactor used to carry out the experiments.

The combined feed streams comprising water W, surfactant SUR,photoinitiator PI and monomer M, are fed to mixing device 5 to form theheterophase medium HM. Via feed line 6, the heterophase medium HM is, inflow direction F, further conveyed to irradiation zone 7 and exits theflow-through reactor 1 via exit line 13. Feed line 6, irradiation zone 7and exit line 13 are designed as a tube from a single piece of a UVtransparent wall material 11.

Emulsion E takes place inside the mixing device 5 typically resulting ina main drop size of below 100 μm. Relaxing and spontaneousemulsification SE occurs after passing the mixing device 5 in feed line6 and typically leads to sub-μm drops.

Irradiation is effected in three zones: In reaction zones RZ1 and RZ2,where irradiation is carried out without cooling and in the mainreaction zone MRZ, where irradiation is carried out by cooling means 12.The total irradiation zone TIZ consists of RZ1, RZ2 and MRZ.

The outflow zone OF is exit line 13.

It is evident that the device described above is also suitable toperform step C). In an embodiment, two reactors are connected in seriesto perform steps A), B) and C) continuously.

Products and Other Aspects of the Present Invention

As a result of the polymerization of step B) polymers, in particularlattices comprising nanoparticles are obtained which are furthermodified in step C).

In an embodiment of the present invention, the aforementioned modifiedpolymers and, in particular, the modified lattices or polymernanoparticles can be used, for example, in coatings, adhesives such asadhesives for laminated glass, inks, painting materials, precision moldconstructions, in the manufacture of electronic articles, for drugdelivery systems, diagnostic sensors and contrast agents.

A further aspect of the present invention therefore relates to coatings,adhesives, inks, and painting materials, precision mold constructions,electronic articles, drug delivery systems, diagnostic sensors andcontrast agents comprising the modified polymers and, in particular, themodified polymer nanoparticles obtained according to the processdescribed herein.

One important achievement is that the polymers obtained according tostep B) simultaneously serve as a building block and as photoinitiatorin step C). The present invention therefore further encompasses the useof polymers comprising phosphorous oxide or phosphorous sulfide groupsin the main polymer chain as photoinitiators.

In an embodiment of the present invention, the present invention relatesto polymers having at least one phosphorous oxide or phosphorous sulfidegroup within the main polymer chain per 10,000 repeating units derivedfrom the monomer or monomers employed in step B), for example, per 1,000repeating units, for example, per 100 repeating units, and the use ofaforementioned polymers as photoinitiators.

The present invention is further illustrated by the examples withoutbeing limited thereto.

EXAMPLES I. General Materials and Methods

The water used throughout was purified using a Seral purification system(PURELAB Plus) or an Integra UV plus (SG Reinstwassersysteme) systemwith a conductivity of 0.06 μS cm⁻¹. Sodium dodecyl sulfate (SDS) (Roth)was used as a surfactant, unless stated otherwise, and was used asreceived. The monomers were distilled under reduced pressure and storedrefrigerated prior to use. The water-soluble photo-initiator2-(bis(2,4,6-trimethylbenzoyl)phosphoryl)acetic acid sodium salt(BAPO-AA-Na) was prepared as described in: T. Ott, Dissertation ETHZürich No. 18055, 2008. 2,4,6-Trimethylbenzoyl-diphenylphosphineoxide(Lucirin TPO, MAPO) and bis(2,4,6-trimethylbenzoyl)-phenylphosphineoxide(Irgacure® 819) were obtained from BASF SE, Germany.

The Continuous Flow-Through Reactor

A microfluidic device as shown in FIGS. 4 and 5 was used as continuousflow reactor (1) for photoinitiated emulsion polymerization.

The feeding system consisted of two gas-tight syringes (2 a, 2 b), one2.5 mL syringe for the monomer (M) and a 10 mL syringe for the aqueousphase containing water (W) photoinitiator (PI) and sodium dodecylsulfate(SUR). Two syringe pumps (3 a, 3 b) were used to feed the reagentsthrough a micromixer (5) and to convey the emulsion formed therein (HM)further through the feed line (6), irradiation zone (7) and exit line(13) to a collection flask (14). The emulsion (HM) was prepared in acountercurrent micromixer (5) (SSIMM) with an inlet channel innerdiameter of 45 μm and an outlet channel inner diameter of 30 μm. Forthis micromixer and a 4 mL/min flow rate, the monomer droplet sizedistribution was quite broad, however, droplets below 1 μm were alsoformed, as was confirmed by light microscopy.

The feed line (6), the exposure zone (7), and the exit line (13) wascommonly formed by a tube of fluorinated poly(ethylene-co-propylene)(FEP), a UV transparent material (12) with an outer diameter of 1.590 mmand an inner diameter of 0.762 mm.

A medium pressure mercury lamp with an arc length of 27.9 cm (450 W,Hanovia) was used as a source of electromagnetic radiation (8, 9),shielded by a 1 mm thick pyrex glass filter (10).

The medium pressure mercury lamp was placed inside a quartz coolingjacket (12) and the FEP tube was wound around this set-up to form theirradiation zone (7).

The average irradiation intensity, calculated on the hemicircularsurface of the heterophase medium within the FEP tube i.e., alsoincluding adsorption of the quartz cooling jacket, the FEP tube and thepyrex filter) was:

168 W/m² at 578.0 nm, 201 W/m² at 546.1 nm 144 W/m² at 435.8 nm, 75 W/m²at 404.5 nm, 147 W/m² at 366.0 nm, 10 W/m² at 334.1 nm, 41 W/m² at 313.0nm, 15 W/m² at 302.5 nm, 6 W/m² at 296.7 nm and 1 W/m² at 289.4 nm.

Therefore, the irradiation intensity for the electromagnetic radiationhaving a wavelength of below 500 nm or below 480 nm or in the range of200 to 480 nm or in the range of 280 to 480 nm was in each case 439W/m².

The temperature in the tube during the reaction was in the range from 25to 30° C., based on temperature measurements taken between the quartzcooling jacket (12) and the tube (7).

Volumes

Total FEP tube volume was 2.7 mL.

-   -   E: emulsification takes place inside the micro-mixer resulting        in a main drop size of below 100 μm. The mixing system used was        a Standard Slit Interdigital Micro Mixer (SSIMM), and was made        of 15 lamellae each with a height of 200 μm, width of 45 μm, and        outflow width of 30 μm.    -   SE: relaxing and spontaneous emulsification after micro-mixer        typically into sub-μm drops.    -   RZ1, 2: irradiation zones, irradiation without cooling.    -   MRZ: main irradiation zone, wound around cooler,    -   TIZ (total irradiation zone)=RZ1+MRZ+RZ2=2.432 mL    -   OF: outflow zone

The SVR of the TIZ was calculated to be 2625 m⁻¹.

Flow Rates and Residence Times

Flow rates of 4 mL/min, 2 mL/min, and 1 mL/min were employed leading toresidence times in the total irradiation zone (TIZ) and thus irradiationtimes of 36 s, 72 s and 144 s, respectively

Latex Characterization

Samples were purified for further characterization by repeatedreprecipitation from tetrahydrofurane in methanol followed by intensewashing with distilled water.

Solid content was determined using a HR73 Halogen Moisture Analyzer(Mettler Toledo). Average particle size (intensity-weighted diameter)was determined with a Nicomp particle sizer (PSS Santa Barbara, USA,model 370) at a fixed scattering angle of 90°.

Molecular weight distributions (MWD) were determined by gel permeationchromatography (GPC) and were used to calculate weight and the number ofaverage molecular weight polymers (Mw, Mn). GPC was carried out byinjecting 100 μL polymer solutions (solvent tetrahydrofuran (THF))through a Teflon-filter with a mesh size of 450 nm into a ThermoSeparation Products set-up equipped with ultra violet (UV) (TSP UV1000),and refractive index (RI) (Shodex RI-71) detectors in THF at 30° C. witha flow rate of 1 mL/min. A column set was employed, which consisted ofthree 300×8 mm columns filled with a MZ-SDplus spherical polystyrene gel(average particle size 5 μm), with pore sizes of 10³, 10⁵, and 10⁶ Å,respectively. Average molecular weights, and number of average molecularweight polymers (Mw and, Mn) were calculated based on polystyrenestandards (between 500 and 2·10⁶ g mol-1 from PSS, Mainz, Germany).

II. Photoinitiated Heterophase Polymerization

Synthesis of Lattices According to Steps A) and B)

All examples were made according to the following procedure: Sodiumdodecylsulfate (SDS), the monomer (2.5 g), degassed water (10.0 g) andthe photoinitiator (PI) were fed into and conveyed through the reactorand irradiated. The temperature during irradiation was 25° C. for allexamples.

Example 1 Monomer: styrene Photoinitiator:2,4,6-trimethylbenzoyl-diphenylphosphineoxide (MAPO)

SDS PI Irradiation Flow rate DLS Solid content Yield Ex. [mg] [mg] time[s] (μl/min) [nm] [%] [%] 1 300 10 36 4000 61 12 62

Examples 2 to 5 Monomer: styrene Photoinitiator:2-(bis(2,4,6-trimethylbenzoyl)phosphoryl)acetic acid sodium salt(BAPO-AA-Na)

SDS PI Irradiation Flow rate DLS Solid content Yield Ex. [mg] [mg] time[s] (μl/min) [nm] [%] [%] 2 200 10 36 4000 51 15 79 3 300 10 36 4000 4519 100 4 400 10 36 4000 38 20 100 5 500 10 36 4000 45 19 100

III. Modification of Polymer Nanoparticles Examples 6 and 7

The lattices obtained according to Examples 1 (to result in Example 6)and 3 (to result in Example 7) were purified by extensive dialysis,however retaining colloidal stability. The lattices were then swollenwith butylmethacrylate (BMA) overnight while gently stirring only thelatex phase with a magnetic stir bar. Formation of macroscopic dropletsof BMA was avoided. A latex sample (2 mL) was collected carefully fromthe bottom of the vial with a pipette in order not to drag swellingagent. The swollen particles were placed in a 6 mL glass flask andirradiated for 2 h while the flask was gently shaken. The latex wascharacterized to determine the solids content, average particle size,and molecular weight distribution.

The results are illustrated in FIGS. 6 and 7.

The latex according to Example 6 (thin dashed lines) and the latexaccording to Example 7 in BMA emulsion (thin solid lines). The molecularweight distribution of the starting polymer is given in bold dashedlines (Example 1) and bold solid lines (Example 3), respectively.

The molecular weight distribution (MWD) of the modified polymers weredetermined by size exclusion chromatography (SEC). A significant changein molecular weight distribution (MWD) occurs after irradiation ineither case as can be seen in FIG. 7.

Furthermore, FT-IR spectroscopic analyses of the lattices of Examples 1and 3 and of the modified polymers after performing step C) in FIG. 6demonstrate that an IR absorption of the carbonyl stretching frequency(*) appears proving that photo-induced modification of the latticesyielded block copolymers of styrene and BMA.

As a control, styrene and BMA were irradiated for two hours but did notpolymerize in the absence of the lattices of Examples 1 and 3.

IV Photoinitiated Bulk Polymerization Examples 8 and 9 Synthesis ofUnmodified Polymers According to Steps A) and B)

A polymerization medium consisting of styrene andbis(2,4,6-trimethylbenzoyl)-phenylphosphineoxide were bulk polymerizedin a weight ratio of 250:1 (Example 8) and 2.5:1 (Example 9) byirradiating it with the following light source: Osram, L18 W, lightcolor 840, lumilux, cool white.

Curves 1 and 2 of FIG. 8 show the unmodified precursor polymer producedin Examples 8 and 9 via bulk polymerization.

It is apparent that increasing the photoinitiator concentration by afactor of 100 shifted the distribution maximum into the low molecularweight region (FIG. 8, curve 2 compared to curve 1).

V. Modification of Polymers Obtained Via Photoinitiated BulkPolymerization Example 10

The polymer obtained in Example 9 was used as photoinitiator andbuilding block simultaneously.

Prior to use the polymer was carefully purified by repeatedreprecipitation from methanol so that no residualbis(2,4,6-trimethylbenzoyl)-phenylphosphineoxide (Irgacure® 819) wasdetectable by ³¹P-NMR.

20 g of water, 600 mg of SDS and 0.5 g of the purified polymer dissolvedin 4 g of styrene were then irradiated at ambient temperature with thesame light source used in Example 9 in the flow through reactor. Themolecular weight distribution of the modified polymer obtained therebyis shown in curve 3 of FIG. 8.

Example 11

10 wt.-% of the polymer obtained in Example 9 were purified as describedin Example 10 and dissolved in vinylacetate. The resulting solution wasspread between a microscopy slide and a cover glass resulting in auniform layer thickness of about 0.1 mm. The solution was thenirradiated through the cover glass using the light source of Examples 8and 9.

Example 12 (Comparative)

Instead of the purified polymer obtained in Example 9, the same amountof a thermally polymerized polystyrene was used. All other conditionswere the same as in Example 11.

Example 13 (Comparative)

Instead of the purified polymer obtained in Example 9, the same amountof a thermally polymerized polystyrene was used. Additionally, 0.5 wt.-%of bis(2,4,6-trimethylbenzoyl)-phenylphosphineoxide (Irgacure® 819)based on n-butylacrylate was added. All other conditions were the sameas in Example 11.

Results of Examples 11, 12, 13

The onset of the polymerization in Example 11 could be followed visuallyby the occurrence of a slight turbidity due to starting microphaseseparation of the block copolymer layer between the glasses (see FIG. 9,two pictures on the left side)

Contrary thereto, the solution employed in Example 12 stayedtransparent, for example, a strongly turbid layer was formed (see FIG.9, upper right side) indicating strong scattering effects at phaseboundaries of the much larger regions where the homopolymers(polystyrene and polybutylacrylate) demix (see FIG. 9, lower rightside).

The light microscopy images of FIG. 9 were taken using a Keyence VHX100microscope under oblique illumination in transmission mode of thepolymer film between the glass slides. The bars indicate 100 μm.

Both the polystyrene-polybutylacrylate block copolymer obtained inExample 11 and the polystyrene polybutylacrylate homopolymer mixtureobtained in Example 13 glued both glass slides together, whereas thecover glass on the non-reactive solution of polystyrene in butylacrylatewithout initiator could be easily removed.

Example 14

10 wt.-% of the polymer obtained in Example 9 were purified as describedin Example 10 and dissolved in vinylacetate in a glass beaker. Theresulting solution was then irradiated through the transparent wallsusing the light source of Examples 8 and 9.

An elastic peace of a polystyrene-polyvinylacetate block copolymer wasobtained having the shape of the beaker. The existence of a blockcopolymer was proven by adding glacial acetic acid which is a selectivesolvent for poly(vinyl acetate). A dispersion was formed indicating theknown stabilization of the “insoluble” polystyrene blocks by the“soluble” polyvinylacetate blocks.

In contrast, adding glacial acetic acid to a mixture of polystyrene andpolyvinylacetate homopolymers resulted in a transparent solutionpolyvinylacetate with free floating chunks of polystyrene.

Example 15

The sequence of letters ‘SRG’ was phototyped through a PTFE stencilusing a 50 wt.-% solution of the polymer obtained in Example 9 purifiedas described in Example 10 in a styrene-butylacrylate mixture (3:2 g/g)with a small amount of a yellow dye. The result is shown in FIG. 10

The present invention is not limited to embodiments described herein;reference should be had to the appended claims.

What is claimed is:
 1. A process for the preparation of a modifiedpolymer by a photo-initiated polymerization, the method comprising: A)preparing a polymerization medium comprising: at least onephotoinitiator comprising at least one phosphorous oxide (P═O) group orat least one phosphorous sulfide (P═S) group, and at least onepolymerizable monomer; B) polymerizing the at least one polymerizablemonomer by irradiating the polymerization medium with electromagneticradiation so as to induce a generation of radicals so as to obtain apolymer; and C) modifying the polymer obtained in B) by irradiating thepolymer with electromagnetic radiation so as to induce a generation ofradicals from the polymer in a presence of at least one modifying agent.2. The process as recited in claim 1, wherein step B) is carried out asa bulk polymerization, a solution polymerization or as a heterophasepolymerization in a heterophase medium.
 3. The process as recited inclaim 2, wherein the process further comprises forming modified latticesor modified polymer nanoparticles by a photo-initiated heterophasepolymerization, the process further comprising: A) preparing aheterophase medium comprising at least a dispersed phase and acontinuous phase and at least: at least one surfactant, at least onephotoinitiator, and at least one polymerizable monomer; B) polymerizingthe at least one polymerizable monomer by irradiating the heterophasemedium with electromagnetic radiation so as to induce a generation ofradicals so as to obtain lattices comprising polymer nanoparticles; andC) modifying the lattices or the polymer nanoparticles by irradiatingthe lattices or the polymer nanoparticles with electromagnetic radiationso as to induce a generation of radicals from the latices or the polymernanoparticles in a presence of the at least one modifying agent,wherein, the at least one photoinitiator is selected from compoundscomprising the at least one phosphorous oxide (P═O) group or the atleast one phosphorous sulfide (P═S) group.
 4. The process as recited inclaim 2, wherein the heterophase medium is provided as an emulsioncomprising an aqueous phase and an organic dispersed phase, the aqueousphase having a pH value in a range of 3 to 10 measured at standardconditions.
 5. The process as recited in claim 1, wherein step A) iscarried out continuously.
 6. The process as recited in claim 1, whereinthe at least one photoinitiator is selected from a compound of formula(I):

wherein n is 1 or 2 or an integer >2, m is 0, 1 or 2, X is sulphur oroxygen, R¹, if n=1 is C₆-C₁₄-aryl or C₃-C₁₄-heterocyclyl, or isC₁-C₁₈-alkoxy, —N(R⁴)₂, C₁-C₁₈-alkyl, C₂-C₁₈-alkenyl or C₂-C₁₈-alkinyl,which is either not, once, twice or more than twice interrupted bynon-successive functional groups selected from the group consisting of:—O—, —S—, —SO₂—, —SO—, —SO₂NR⁴—, NR⁴SO₂—, —NR⁴—, —N⁺(R⁴)₂An⁻-, —CO—,—O(CO)—, (CO)O—, —O(CO)O—, —NR⁴(CO)NR⁴—, NR⁴(CO)—, —(CO)NR⁴—,—NR⁴(CO)O—, —O(CO)NR⁴—, —Si(R⁵)₂—, —OSi(R⁵)₂—, —OSi(R⁵)₂O—, and—Si(R⁵)₂O—, and which is either not, once, twice or more than twiceinterrupted by bivalent residues selected from the group consisting ofC₃-C₁₄-heterocyclo-diyl, C₃-C₁₄-heterocyclo-diylium⁺An⁻ andC₆-C₁₄-aryldiyl, and which is not, additionally or alternatively eitheronce, twice or more than twice substituted by substituents selected fromthe group consisting of: halogen, cyano, azido, vicinal oxo (formingepoxides), vicinal NR⁵ (forming aziridins), C₆-C₁₄-aryl, C₁-C₈-alkoxy,C₁-C₈-alkylthio, hydroxy, —SO₃M, —COOM, PO₃M₂, —PO(N(R⁵)₂)₂, PO(OR⁵)₂,—SO₂N(R⁴)₂, —N(R⁴)₂, —N⁺(R⁴)₃An⁻, C₃-C₁₄-heterocyclylium⁺An⁻,—CO₂N(R⁴)₂, —COR⁴, —OCOR⁴, —NR⁴(CO)R⁵, —(CO)OR⁴, —NR⁴(CO)N(R⁴)₂,NR⁴SO₂R⁴, (OR⁵)_(y)(R⁵)_((3-y)), and —OSi(OR⁵)_(y)(R⁵)_((3-y)) with y=1,2 or 3, R¹, if n=2 is C₆-C₁₅-aryldiyl or C₃-C₁₄-heterocyclo-diyl, or isC₁-C₁₈-alkanediyl, C₂-C₁₈-alkenediyl or C₂-C₁₈-alkinediyl, which iseither not, once, twice or more than twice interrupted by non-successivegroups selected from the group consisting of: —O—, —S—, —SO₂—, —SO—,—SO₂NR⁴—, NR⁴SO₂—, —NR⁴—, —N⁺(R⁴)₂An⁻-, —CO—, —O(CO)—, (CO)O—, —O(CO)O—,—NR⁴(CO)NR⁴—, NR⁴(CO)—, —(CO)NR⁴—, —NR⁴(CO)O—, —O(CO)NR⁴—, —Si(R⁵)₂—,—OSi(R⁵)₂—, —OSi(R⁵)₂O—, and —Si(R⁵)₂O—, and which is either not, once,twice or more than twice interrupted by bivalent residues selected fromthe group consisting of C₃-C₁₄-heterocyclo-diyl, C₃-C₁₄—heterocyclo-diylium⁺An⁻ and C₆-C₁₄-aryldiyl, and which is not,additionally or alternatively either once, twice or more than twicesubstituted by substituents selected from the group consisting of:halogen, cyano, azido, vicinal oxo (forming epoxides), vicinal NR⁵(forming aziridins), C₆-C₁₄-aryl, C₁-C₈-alkoxy, C₁-C₈-alkylthio,hydroxy, —SO₃M, —COOM, PO₃M₂, —PO(N(R⁵)₂)₂, PO(OR⁵)₂, —SO₂N(R⁴)₂,—N(R⁴)₂, —N⁺(R⁴)₃An⁻, C₃-C₁₄-heterocyclylium⁺An⁻, —CO₂N(R⁴)₂, —COR⁴,—OCOR⁴, —NR⁴(CO)R⁵, —(CO)OR⁴, —NR⁴(CO)N(R⁴)₂, NR⁴SO₂R⁴,—Si(OR⁵)_(y)(R⁵)_((3-y)), —OSi(OR⁵)_(y)(R⁵)_((3-y)) with y=1, 2 or 3, oris bivalent bis(C₆-C₁₅)-aryl, which is either not or once interrupted bygroups selected from the group consisting of: —O—, —S—, —SO₂—, —SO—,C₄-C₁₈-alkanediyl, and C₂-C₁₈-alkenediyl, R¹, if n is an integer >2 is apolymeric backbone having n binding sites to residues of formula (I)given in brackets labeled with n, R² is C₆-C₁₄-aryl orC₃-C₁₄-heterocyclyl, or is C₁-C₁₈-alkyl, C₂-C₁₈-alkenyl orC₂-C₁₈-alkinyl, which is either not, once, twice or more than twiceinterrupted by non-successive functional groups selected from the groupconsisting of: —O—, —NR⁴—, —N⁺(R⁴)₂An⁻-, —CO—, —OCO—, —O(CO)O—,NR⁴(CO)—, —NR⁴(CO)O—, O(CO)NR⁴—, and —NR⁴(CO)NR⁴—, and which is eithernot, once, twice or more than twice interrupted by bivalent residuesselected from the group consisting of heterocyclo-diyl,heterocyclo-diylium⁺An⁻, and C₆-C₁₄-aryldiyl, and which is not,additionally or alternatively either once, twice or more than twicesubstituted by substituents selected from the group consisting of:halogen, cyano, hydroxy, protected hydroxyl, C₆-C₁₄-aryl;C₃-C₁₄-heterocyclyl, C₁-C₈-alkoxy, C₁-C₈-alkylthio, C₂-C₈-alkenyl,—COOM, —SO₃M, —PO₃M₂, —SO₂N(R⁴)₂, —NR⁴SO₂R⁵, —N(R⁴)₂—, —N⁺(R⁴)₃An⁻,—CO₂N(R⁴)₂, —COR⁴—, —OCOR⁵, —O(CO)OR⁵, NR⁴(CO)R⁴, —NR⁴(CO)OR⁴,O(CO)N(R⁴)₂, and —NR⁴(CO)N(R⁴)₂, wherein, when m=2, the two substituentsR² are different, identical, or jointly are C₆-C₁₅-aryldiyl,C₃-C₁₄-heterocyclo-diyl, C₁-C₁₈-alkanediyl, C₂-C₁₈-alkenediyl orC₂-C₁₈-alkinediyl, R³ independently denotes a substituent as defined forR¹ if n is 1, wherein, R⁴ is independently selected from the groupconsisting of hydrogen, C₁-C₈-alkyl, C₆-C₁₄-aryl andC₃-C₁₄-heterocyclyl, or N(R⁴)₂ as a whole is an N-containingC₃-C₁₄-heterocycle, or N⁺(R⁴)₂An⁻ and N⁺(R⁴)₃An⁻ as a whole are orcontain an N-containing C₃-C₁₄-heterocyclyl substituent with acounteranion, R⁵ is independently selected from the group consisting ofC₁-C₈-alkyl, C₆-C₁₄-aryl and C₃-C₁₄-heterocyclyl, or N(R⁵)₂ as a wholeis an N-containing C₃-C₁₄-heterocycle, or N⁺(R⁵)₂An⁻ and N⁺(R⁵)₃An⁻ as awhole are or contain an N-containing C₃-C₁₄-heterocyclyl substituentwith a counteranion, M is hydrogen, or a 1/q equivalent of an q-valentmetal ion, or is a C₃-C₁₄-heterocyclylium cation, an ammonium ion, or aprimary organic ammonium, a secondary organic ammonium, a tertiaryorganic ammonium or a quarternary organic ammonium ion, or a guanidiniumion, or an organic guanidinium ion, and An− is a 1/p equivalent of ap-valent anion.
 7. The process as recited in claim 6, wherein the atleast one photoinitiator is selected from compounds of formula (I)where: X is oxygen, n is 1, m is 1 or 2, R¹ and R³ are, independently ofeach other, C₆-C₁₄-aryl, or are C₁-C₁₈-alkyl, which is either not oronce, twice or more than twice interrupted by non-successive functionalgroups selected from the group consisting of —O— and —NR⁴—, and which isnot, additionally or alternatively, either not, once, twice or more thantwice, substituted by substituents selected from the group consisting ofchloro, fluoro, C₁-C₈-alkoxy, hydroxy, —SO₃M, —COOM, PO₃M₂, SO₂N(R⁴)₂,—N(R⁴)₂, —N⁺(R⁴)₃An⁻, and —CO₂N(R⁴)₂, R² is C₆-C₁₄-aryl, wherein, whenm=2, the substituents R² are different or identical, wherein, R⁴ isindependently selected from the group consisting of C₁-C₈-alkyl,C₆-C₁₄-aryl and C₃-C₁₄-heterocyclyl, or N(R⁴)₂ as a whole is anN-containing C₃-C₁₄-heterocycle, or N⁺(R⁴)₂An⁻ and N⁺(R⁴)₃An⁻ as a wholeare or contain an N-containing C₃-C₁₄-heterocyc lyl substituent with acounteranion, M is hydrogen, or a 1/q equivalent of a q-valent metal ionor is a C₃-C₁₄-heterocyclylium cation, an ammonium ion or a primaryorganic ammonium, a secondary organic ammonium, a tertiary organicammonium or a quarternary organic ammonium ion, or a guanidinium ion oran organic guanidinium ion, lithium, sodium, potassium, one halfequivalent of calcium, zinc or iron (II), or one third equivalent ofaluminium (III) or a C₃-C₁₄-heterocyclylium cation or an ammonium ion ora primary organic ammonium, a secondary organic ammonium, a tertiaryorganic ammonium or a quarternary organic ammonium ion, and An⁻ is a lipequivalent of a p-valent anion, a C₁-C₈-alkyl carboxylate, C₁-C₈-alkylsulfate, C₆-C₁₄-aryl sulfate, hexafluorophosphate, tetrafluoroborate,dihydrogenphosphate, one half equivalent of sulphate orhydrogenphosphate.
 8. The process as recited in claim 1, wherein the atleast one photoinitiator is selected from2-(bis(2,4,6-trimethylbenzoyl)phosphoryl)acetic acid and its salts,(2-(2-(2-methoxyethoxy)ethoxy)ethyl)-(bis(2,4,6-trimethylbenzoyl)-phosphineoxide,2,4,6-trimethylbenzoyl-diphenylphosphineoxide andbis(2,4,6-trimethylbenzoyl)-phenylphosphineoxide.
 9. The process asrecited in claim 1, wherein the at least one polymerizable monomer isselected of the group consisting of compounds of formula (IIa) andformula (IIb):

wherein, R⁶, R⁷, R⁸ and R⁹ are, independently of one another, selectedfrom the group consisting of: hydrogen, C₆-C₁₄-aryl,C₃-C₁₄-heterocyclyl, C₁-C₁₈-alkoxy, C₁-C₁₈-alkyl, C₂-C₁₈-alkenyl andC₂-C₁₈-alkinyl, which is either directly bound to a double bond informula (IIa) or, in case of C₆-C₁₄-aryl, C₃-C₁₄-heterocyclyl,C₁-C₁₈-alkyl, C₂-C₁₈-alkenyl and C₂-C₁₈-alkinyl, alternatively, via afunctional group selected from the group consisting of: —CO—, —OCO—,—O(CO)O—, NR⁴(CO)—, —NR⁴(CO)O—, —O(CO)NR⁴—, —(CO)NR⁴—, —NR⁴(CO)NR⁴—,—Si(R⁵)₂—, —OSi(R⁵)₂—, —OSi(R⁵)₂O—, —Si(R⁵)₂O—, and, which is eithernot, once, twice or more than twice, interrupted by non-successivefunctional groups selected from the group consisting of: —O—, —CO—,—OCO—, —O(CO)O—, NR⁴(CO)—, —NR⁴(CO)O—, —O(CO)NR⁴—, —(CO)NR⁴—,—NR⁴(CO)NR⁴—, —Si(R⁵)₂—, —OSi(R⁵)₂—, —OSi(R⁵)₂O—, —Si(R⁵)₂O—, and whichis additionally or alternatively, either not, once, twice or more thantwice, interrupted by bivalent residues selected from the groupconsisting of C₃-C₁₄-heterocyclo-diyl and C₆-C₁₄-aryldiyl, and which isnot, additionally or alternatively, either once, twice or more thantwice substituted by substituents selected from the group consisting of:halogen, cyano, vicinal oxo (forming epoxides), vicinal NR⁵ (formingaziridins), C₆-C₁₄-aryl; C₃-C₁₄-heterocyclyl, C₁-C₈-alkylthio, hydroxy,—SO₂N(R⁴)₂, NR⁴SO₂—R⁵, —N(R⁴)₂, —CO₂N(R⁴)₂, —COR⁴, —OCOR⁴, —O(CO)OR⁴,NR⁴(CO)R⁵, —NR⁴(CO)OR⁵, O(CO)N(R⁴)₂, —NR⁴(CO)N(R⁴)₂,—OSi(OR⁵)_(y-3)(R⁵)_(y), —Si(OR⁵)_(y-3)(R⁵)_(y) where y is 1, 2 or 3 or,wherein two residues of R⁶, R⁷, R⁸ and R⁹ together are C₂-C₁₈-alkanediylor C₃-C₁₈-alkenediyl

wherein, R⁶, R⁷ and R⁸ are as set forth for formula (IIa), Or, whereintwo residues of R⁶, R⁷ and R⁸ together are C₂-C₁₈-alkanediyl orC₃-C₁₈-alkenediyl, and wherein, t is an integer from 2 to 4, and Y ismissing such that R¹⁰ is directly bound to a double bond in formula(IIb) or is —CO— or —(CO)O—, and R¹⁰ is a t-valent residue selected fromthe group consisting of C₂-C₁₈-alkanediyl (t=2), C₃-C₁₈-alkanetriyl(t=3), C₄-C₁₈-alkanetetrayl (t=4), C₂-C₁₈-alkenediyl (t=2),C₃-C₁₈-alkenetriyl (t=3), C₄-C₁₈-alkenetetrayl (t=4), C₂-C₁₈-alkinediyl(t=2), C₆-C₁₄-aryldiyl (t=2) and C₃-C₁₄-heterocyclodiyl (t=2).
 10. Theprocess as recited in claim 1, wherein the at least one polymerizablemonomer is selected from: methyl-, ethyl-, n-butyl-, glycidyl-,2-ethylhexyl- and 2-hydroxyethyl acrylate; acrylamide,N-isopropylacrylamide, and acrylonitrile; methyl-, ethyl-, n-butyl-,glycidyl-, 2-ethylhexyl-, 2-hydroxyethyl and is obornyl methacrylate;methacrylamide, N-isopropylmethacrylamide and methacrylonitrile;crotonic acid, maleic acid, fumaric acid, itaconic acid, cinnamic acidand linolenic acid or oleic acid and the respective C₁-C₈-alkyl estersthereof and C₁-C₈-alkyl diesters; ethyl vinyl ether and isobutyl vinylether; vinyl acetate; vinylpyridine, styrene and styrene substituted byC₁-C₈-alkyl-, halogen, or sulfonic acid salts at an aromatic ring;trimethoxyvinylsilane and triethoxyvinylsilan; ethylene glycoldiacrylate, 1,6-hexanediol diacrylate, propylene glycol diacrylate,dipropylene glycol diacrylate, tripropylene glycol diacrylate, neopentylglycol diacrylate, hexamethylene glycol diacrylate and bis-phenol-Adiacrylate, 4,4′-bis(2-acryloyloxyethoxy)diphenylpropane,trimethylolpropane tri-acrylate, pentaerythritol triacrylate,pentaerythritol tetraacrylate, vinyl acrylate,polyethyleneglycol-mono-acrylate, polyethylene-glycol-di-acrylate,ethylene glycol dimethacrylate, 1,6-hexanediol dimethacrylate, propyleneglycol dimethacrylate, dipropylene glycol dimethacrylate, tripropyleneglycol dimethacrylate, neopentyl glycol dimethacrylate, hexamethyleneglycol dimethacrylate and bis-phenol-A dimethacrylate,4,4′-bis(2-methacryloyloxyethoxy)diphenylpropane, trimethylolpropanetri-methacrylate, pentaerythritol trimethacrylate, pentaerythritoltetramethacrylate, vinyl methacrylate,polyethyleneglycol-mono-methacrylate, andpolyethylene-glycol-di-methacrylate; butadiene, isoprene, chloroprene,2,4-dimethylbutadiene, cyclopentadiene, methylcyclopentadiene,cyclohexadiene, divinyl-benzene, 1-vinyl-cyclohexadiene, norbornadiene,2-isopropenylnorbornene, 2-vinyl-norbornene, diisopropenylbenzene,divinyltoluene, divinylxylene and C₁ to C₂₀ alkyl-substitutedderivatives of the aforementioned divinylaromatic multiolefins, divinylsuccinate, diallyl phthalate, triallyl phosphate, triallyl isocyanurate,tris-(hydroxyethyl) isocyanurate triacrylate (Sartomer 368; from CrayValley), tris(2-acryloyl-ethyl) isocyanurate,ethyleneglycoldivinylether, diethyleneglycoldivinylether, andtriethylene-glycoldivinylether, and any mixture thereof.
 11. The processas recited in claim 1, wherein, in at least one of step B) and step C),the irradiating of the poolymerization medium is effected so that aratio of an irradiated surface of the polymerization medium to a volumeof the polymerization medium is at least 600 m⁻¹.
 12. The process asrecited in claim 1, wherein, in at least one of step B) and step C), theirradiating is effected with electromagnetic radiation having awavelength of below 500 nm.
 13. The process as recited in claim 1,wherein, in at least one of step B) and step C), the irradiating iseffected at an average intensity of at least 50 W per square meter of anirradiated surface of the polymerization medium.
 14. The process asrecited in claim 9 or 10, wherein the at least one modifying agent isselected from the at least one polymerizable monomer as recited in claim9 or 10, the at least one polymerizable monomer being different from theat least one polymerizable monomer of steps A) and B).
 15. The processas recited in claim 1, wherein the modified polymer is a blockcopolymer,a crosslinked polymer, a telechelic polymer or a functionalizedblockcopolymer.